On the second deck there were no large compartments, only long corridors lined with grey circles along the centre of the walls. Antonio used a dimple at the side of one, and it dilated to reveal a spherical cell three metres wide. Its walls were translucent, with short lines of colour slithering round behind them like photonic fish.

«Beds?» Schutz suggested. «There's an awful lot of them.»

Marcus shrugged. «Could be.» He moved on, eager to get down to the next deck. Then he slowed, switching his collar focus. Three of the hemispherical blisters were following him, two gliding along the wall, one on the floor. They stopped when he did. He walked over to the closest, and waved his sensor block over it. «There's a lot of electronic activity inside it,» he reported.

The others gathered round.

«Are they extruded by the wall, or are they a separate device?» Schutz asked.

Marcus switched on the block's resonance scan. «I'm not sure, I can't find any break in the composite round its base, not even a hairline fracture; but with their materials technology that doesn't mean much.»

«Five more approaching,» Jorge datavised. The blisters were approaching from ahead, three of them on the walls, two on the floor. They stopped just short of the group.

«Something knows we're here,» Antonio datavised.

Marcus retrieved the CAB xenoc interface communication protocol from a neural nanonics memory cell. He'd stored it decades ago, all qualified starship crew were obliged to carry it along with a million and one other bureaucratic lunacies. His communication block transmitted the protocol using a multi-spectrum sweep. If the blister could sense them, it had to have some kind of electromagnetic reception facility. The communication block switched to laserlight, then a magnetic pulse.

«Nothing,» Marcus datavised.

«Maybe the central computer needs time to interpret the protocol,» Schutz datavised.

«A desktop block should be able to work that out.»

«Perhaps the computer hasn't got anything to say to us.»

«Then why send the blisters after us?»

«They could be autonomous, whatever they are.»

Marcus ran his sensor block over the blister again, but there was no change to its electronic pattern. He straightened up, wincing at the creak of complaint his spine made at the heavy gravity. «OK, our hour is almost up anyway. We'll get back to Lady Mac and decide what stage two is going to be.»

The blisters followed them all the way back to the stairwell they'd used. As soon as they started walking down the broad central hallway of the upper deck, more blisters started sliding in from compartments and other halls to stalk them.

The airlock hatch was still open when they got back, but the exoskeletons were missing.

«Shit,» Antonio datavised. «They're still here, the bloody xenocs are here.»

Marcus shoved his fingers into the dimple. His heartbeat calmed considerably when the hatch congealed behind them. The lock cycled obediently, and the outer rectangle opened.

«Wai,» he datavised. «We need a lift. Quickly, please.»

«On my way, Marcus.»

«Strange way for xenocs to communicate,» Schutz datavised. «What did they do that for? If they wanted to make sure we stayed, they could have disabled the airlock.»

The MSV swooped over the edge of the shell, jets of twinkling flame shooting from its thrusters.

«Beats me,» Marcus datavised. «But we'll find out.»

Marcus called his council of war five hours later, once everyone had a chance to wash, eat, and rest. Opinion was a straight split: the crew wanted to continue investigating the xenoc ship, Antonio and his colleagues wanted to leave. For once Jorge had joined them, which Marcus considered significant. He was beginning to think young Karl might have been closer to the truth than was strictly comfortable.

«The dish is just rock with a coating of aluminium sprayed on,» Katherine said. «There's very little aluminium left now, most of it has boiled away. The tower is a pretty ordinary silicon/boron composite wrapped round a titanium load structure. The samples Wai cut off were very brittle.»

«Did you carbon-date them?» Victoria asked.

«Yeah.» She gave her audience a laboured glance. «Give or take a decade, it's thirteen thousand years old.»

Breath whistled out of Marcus's mouth. «Jesus.»

«Then they must have been rescued, or died,» Roman said. «There's nobody left over there. Not after that time.»

«They're there,» Antonio growled. «They stole our exoskeletons.»

«I don't understand what happened to the exoskeletons. Not yet. But any entity who can build a ship like that isn't going to go creeping round stealing bits of space armour. There has to be a rational explanation.»

«Yes! They wanted to keep us over there.»

«What for? What possible reason would they have for that?»

«It's a warship, it's been in battle. The survivors don't know who we are, if we're their old enemies. If they kept us there, they could study us and find out.»

«After thirteen thousand years, I imagine the war will be over. And where did you get this battleship idea from anyway?»

«It's a logical assumption,» Jorge said quietly.

Roman turned to Marcus. «My guess is that some kind of mechanoid picked them up. If you look in one of the lockers you'll probably find them neatly stored away.»

«Some automated systems are definitely still working,» Schutz said. «We saw the blisters. There could be others.»

«That seems the most remarkable part of it,» Marcus said. «Especially now we know the age of the thing. The inside of that ship was brand new. There wasn't any dust, any scuff marks. The lighting worked perfectly, so did the gravity, the humidity hasn't corroded anything. It's extraordinary. As if the whole structure has been in zero-tau. And yet only the shell is protected by the molecular-bonding-force generators. They're not used inside, not in the decks we examined.»

«However they preserve it, they'll need a lot of power for the job, and that's on top of gravity generation and environmental maintenance. Where's that been coming from uninterrupted for thirteen thousand years?»

«Direct mass-to-energy conversion,» Katherine speculated. «Or they could be tapping straight into the sun's fusion. Whatever, bang goes the Edenist He3 monopoly.»

«We have to go back,» Marcus said.

«NO!» Antonio yelled. «We must find the gold first. When that has been achieved, you can come back by yourselves. I won't allow anything to interfere with our priorities.»

«Look, I'm sorry you had a fright while you were over there. But a power supply that works for thirteen thousand years is a lot more valuable than a whole load of gold which we have to sell furtively,» Katherine said levelly.

«I hired this ship. You do as I say. We go after the gold.»

«We're partners, actually. I'm not being paid for this flight unless we strike lucky. And now we have. We've got the xenoc ship, we haven't got any gold. What does it matter to you how we get rich, as long as we do? I thought money was the whole point of this flight.»

Antonio snarled at her, and flung himself at the floor hatch, kicking off hard with his legs. His elbow caught the rim a nasty crack as he flashed through it.

«Victoria?» Marcus asked as the silence became strained. «Have the satellite arrays found any heavy metal particles yet?»

«There are definitely traces of gold and platinum, but nothing to justify a rendezvous.»

«In that case, I say we start to research the xenoc wreck properly.» He looked straight at Jorge. «How about you?»

«I think it would be prudent. You're sure we can continue to monitor the array satellites from here?»

«Yes.»

«Good. Count me in.»

«Thanks. Victoria?»

She seemed troubled by Jorge's response, even a little bewildered, but she said: «Sure.»

«Karl, you're the nearest thing we've got to a computer expert. I want you over there trying to make contact with whatever control network is still operating.»

«You got it.»

«From now on we go over in teams of four. I want sensors put up to watch the airlocks when we're not around, and I want some way of communicating with people inside. Start thinking. Wai, you and I are going to secure Lady Mac to the side of the shell. OK, let's get active, people.»

Unsurprisingly, none of the standard astronautics industry vacuum epoxies worked on the shell. Marcus and Wai wound up using tether cables wrapped round the whole of the xenoc ship to hold Lady Mac in place.

Three hours after Karl went over, he asked Marcus to join him.

Lady Mac 's main airlock tube had telescoped out of the hull to rest against the shell. There was no way it could ever be mated to the xenoc airlock rectangle, but it did allow the crew to transfer over directly without having to use exoskeleton armour and the MSV. They'd also run an optical fibre through the xenoc airlock to the interior of the ship. The hatch material closed around it forming a perfect seal, rather than slicing it in half.

Marcus found Karl just inside the airlock, sitting on the decking with several processor blocks in his lap. Eight blisters were slowly circling round him; two on the wall were stationary.

«Roman was almost right,» he datavised as soon as Marcus stepped out of the airlock. «Your exoskeletons were cleared away. But not by any butler mechanoid. Watch.» He lobbed an empty recording flek case onto the floor behind the blisters. One of them slid over to it. The green composite became soft, then liquid. The little plastic case sank through it into the blister.

«I call them cybermice,» Karl datavised. «They just scurry around keeping the place clean. You won't see the exoskeletons again, they ate them, along with anything else they don't recognize as part of the ship's structure. I imagine they haven't tried digesting us yet because we're large and active; maybe they think we're friends of the xenocs. But I wouldn't want to try sleeping over here.»

«Does this mean we won't be able to put sensors up?»

«Not for a while. I've managed to stop them digesting the communication block which the optical fibre is connected to.»

«How?»

He pointed to the two on the wall. «I shut them down.»

«Jesus, have you accessed a control network?»

«No. Schutz and I used a micro SQUID on one of the cybermice to get a more detailed scan of its electronics. Once we'd tapped the databus traffic it was just a question of running standard decryption programs. I can't tell you how these things work, but I have found some basic command routines. There's a deactivation code which you can datavise to them. I've also got a reactivation code, and some directional codes. The good news is that the xenoc program language is standardized.» He stood and held a communication block up to the ceiling. «This is the deactivation code.» A small circle of the ceiling around the block turned dark. «It's only localized, I haven't worked out how to control entire sections yet. We need to trace the circuitry to find an access port.»

«Can you turn it back on again?»

«Oh yes.» The dark section flared white again. «The codes work for the doors as well; just hold your block over the dimples.»

«Be quicker to use the dimples.»

«For now, yes.»

«I wasn't complaining, Karl. This is an excellent start. What's your next step?»

«I want to access the next level of the cybermice program architecture. That way I should be able to load recognition patterns in their memory. Once I can do that I'll enter our equipment, and they should leave it alone. But that's going to take a long time; Lady Mac isn't exactly heavily stocked with equipment for this kind of work. Of course, once I do get deeper into their management routines we should be able to learn a lot about their internal systems. From what I can make out the cybermice are built around a molecular synthesizer.» He switched on a fission knife, its ten-centimetre blade glowing a pale yellow under the ceiling's glare. It scored a dark smouldering scar in the composite.

A cybermouse immediately slipped towards the blemish. This time when the composite softened the charred granules were sucked down, and the small valley closed up.

«Exactly the same thickness and molecular structure as before,» Karl datavised. «That's why the ship's interior looks brand new, and everything's still working flawlessly after thirteen thousand years. The cybermice keep regenerating it. Just keep giving them energy and a supply of mass and there's no reason this ship won't last for eternity.»

«It's almost a von Neumann machine, isn't it?»

«Close. I expect a synthesizer this small has limits. After all, if it could reproduce anything, they would have built themselves another starship. But the principle's here, Captain. We can learn and expand on it. Think of the effect a unit like this will have on our manufacturing industry.»

Marcus was glad he was in an SII suit, it blocked any giveaway facial expressions. Replicator technology would be a true revolution, restructuring every aspect of human society, Adamist and Edenist alike. And revolutions never favoured the old.

I just came here for the money, not to destroy a way of life for eight hundred star systems.

«That's good, Karl. Where did the others go?»

«Down to the third deck. Once we solved the puzzle of the disappearing exoskeletons, they decided it was safe to start exploring again.»

«Fair enough, I'll go down and join them.»

«I cannot believe you agreed to help them,» Antonio stormed. «You of all people. You know how much the cause is depending on us.»

Jorge gave him a hollow smile. They were together in his sleeping cubicle, which made it very cramped. But it was one place on the starship he knew for certain no sensors were operational; a block he'd brought with him had made sure of that. «The cause has become dependent on your project. There's a difference.»

«What are you talking about?»

«Those detector satellites cost us a million and a half fuseodollars each; and most of that money came from sources who will require repayment no matter what the outcome of our struggle.»

«The satellites are a hell of a lot cheaper than antimatter.»

«Indeed so. But they are worthless to us unless they find pitchblende.»

«We'll find it. Victoria says there are plenty of traces. It's only a question of time before we get a big one.»

«Maybe. It was a good idea, Antonio, I'm not criticizing. Fusion bomb components are not easily obtainable to a novice political organization with limited resources. One mistake, and the intelligence agencies would wipe us out. No, old-fashioned fission was a viable alternative. Even if we couldn't process the uranium up to weapons quality, we can still use it as a lethal large-scale contaminate. As you say, we couldn't lose. Sonora would gain independence, and we would form the first government, with full access to Treasury. Everyone would be reimbursed for their individual contribution to the liberation.»

«So why are we fucking about in a pile of xenoc junk? Just back me up, Jorge, please. Calvert will leave it alone if we both pressure him.»

«Because, Antonio, this piece of so-called xenoc junk has changed the rules of the game. In fact we're not even playing the same game any more. Gravity generation, an inexhaustible power supply, molecular synthesis, and if Karl can access the control network he might even find the blueprints to build whatever stardrive they used. Are you aware of the impact such a spectrum of radical technologies will have upon the Confederation when released all together? Entire industries will collapse from obsolescence overnight. There will be an economic depression the like of which we haven't seen since before the invention of the ZTT drive. It will take decades for the human race to return to the kind of stability we enjoy today. We will be richer and stronger because of it; but the transition years, ah . . . I would not like to be a citizen in an asteroid settlement that has just blackmailed the founding company into premature independence. Who is going to loan an asteroid such as that the funds to re-equip our industrial stations, eh?»

«I . . . I hadn't thought of that.»

«Neither has the crew. Except for Calvert. Look at his face next time you talk to him, Antonio. He knows, he has reasoned it out, and he's seen the end of his captaincy and freedom. The rest of them are lost amid their dreams of exorbitant wealth.»

«So what do we do?»

Jorge clamped a hand on Antonio's shoulder. «Fate has smiled on us, Antonio. This was registered as a joint venture flight. No matter we were looking for something different. By law, we are entitled to an equal share of the xenoc technology. We are already trillionaires, my friend. When we get home we can buy Sonora asteroid; Holy Mother, we can buy the entire Lagrange cluster.»

Antonio managed a smile, which didn't quite correspond with the dew of sweat on his forehead. «OK, Jorge. Hell, you're right. We don't have to worry about anything any more. But . . .»

«Now what?»

«I know we can pay off the loan on the satellites, but what about the Crusade council? They won't like this. They might—«

«There's no cause for alarm. The council will never trouble us again. I maintain that I am right about the disaster which destroyed the xenoc ship. It didn't have an accident. That is a warship, Antonio. And you know what that means, don't you? Somewhere on board there will be weapons just as advanced and as powerful as the rest of its technology.»

It was Wai's third trip over to the xenoc ship. None of them spent more than two hours at a time inside. The gravity field made every muscle ache, walking round was like being put on a crash exercise regimen.

Schutz and Karl were still busy by the airlock, probing the circuitry of the cybermice, and decrypting more of their programming. It was probably the most promising line of research; once they could use the xenoc program language they should be able to extract any answer they wanted from the ship's controlling network. Assuming there was one. Wai was convinced there would be. The number of systems operating—life-support, power, gravity—had to mean some basic management integration system was functional.

In the meantime there was the rest of the structure to explore. She had a layout file stored in her neural nanonics, updated by the others every time they came back from an excursion. At the blunt end of the wedge there could be anything up to forty decks, if the spacing was standard. Nobody had gone down to the bottom yet. There were some areas which had no obvious entrance; presumably engineering compartments, or storage tanks. Marcus had the teams tracing the main power lines with magnetic sensors, trying to locate the generator.

Wai plodded after Roman as he followed a cable running down the centre of a corridor on the eighth deck.

«It's got so many secondary feeds it looks like a fish-bone,» he complained. They paused at a junction with five branches and he swept the block round. «This way.» He started off down one of the new corridors.

«We're heading towards stairwell five,» she told him, as the layout file scrolled through her skull.

There were more cybermice than usual on deck eight; over thirty were currently pursuing her and Roman, creating strong ripples in the composite floor and walls. Wai had noticed that the deeper she went into the ship the more of them there seemed to be. Although after her second trip she'd completely ignored them. She wasn't paying a lot of attention to the compartments leading off from the corridors, either. It wasn't that they were all the same, rather that they were all similarly empty.

They reached the stairwell, and Roman stepped inside. «It's going down,» he datavised.

«Great, that means we've got another level to climb up when we're finished.»

Not that going down these stairs was easy, she acknowledged charily. If only they could find some kind of variable gravity chute. Perhaps they'd all been positioned in the part of the ship that was destroyed.

«You know, I think Marcus might have been right about the dish being an emergency beacon,» she datavised. «I can't think of any other reason for it being built. Believe me, I've tried.»

«He always is right. It's bloody annoying, but that's why I fly with him.»

«I was against it because of the faith gap.»

«Say what?»

«The amount of faith these xenocs must have had in themselves. It's awesome. So different from humans. Think about it. Even if their homeworld is only two thousand light-years away, that's how long the message is going to take to reach there. Yet they sent it believing someone would still be around to receive it, and more, act on it. Suppose that was us; suppose the Lady Mac had an accident a thousand light-years away. Would you think there was any point in sending a lightspeed message to the Confederation, then going into zero-tau to wait for a rescue ship?»

«If their technology can last that long, then I guess their civilization can, too.»

«No, our hardware can last for a long time. It's our culture that's fragile, at least compared to theirs. I don't think the Confederation will last a thousand years.»

«The Edenists will be here, I expect. So will all the planets, physically if nothing else. Some of their societies will advance, possibly even to a state similar to the Kiint; some will revert to barbarism. But there will be somebody left to hear the message and help.»

«You're a terrible optimist.»

They arrived at the ninth deck, only to find the doorway was sealed over with composite.

«Odd,» Roman datavised. «If there's no corridor or compartment beyond, why put a doorway here at all?»

«Because this was a change made after the accident.»

«Could be. But why would they block off an interior section?»

«I've no idea. You want to keep going down?»

«Sure. I'm optimistic enough not to believe in ghosts lurking in the basement.»

«I really wish you hadn't said that.»

The tenth deck had been sealed off as well.

«My legs can take one more level,» Wai datavised. «Then I'm going back.»

There was a door on deck eleven. It was the first one in the ship to be closed.

Wai stuck her fingers in the dimple, and the door dilated. She edged over cautiously, and swept the focus of her collar sensors round. «Holy shit. We'd better fetch Marcus.»

Decks nine and ten had simply been removed to make the chamber. Standing on the floor and looking up, Marcus could actually see the outline of the stairwell doorways in the wall above him. By xenoc standards it was a cathedral. There was only one altar, right in the centre. A doughnut of some dull metallic substance, eight metres in diameter with a central aperture five metres across; the air around it was emitting a faint violet glow. It stood on five sable-black arching buttresses, four metres tall.

«The positioning must be significant,» Wai datavised. «They built it almost at the centre of the wreck. They wanted to give it as much protection as possible.»

«Agreed,» Katherine replied. «They obviously considered it important. After a ship has suffered this much damage, you don't expend resources on anything other than critical survival requirements.»

«Whatever it is,» Schutz reported, «it's using up an awful lot of power.» He was walking round it, keeping a respectful distance, wiping a sensor block over the floor as he went. «There's a power cable feeding each of those legs.»

«Is it radiating in any spectrum?» Marcus asked.

«Only that light you can see, which spills over into ultraviolet, too. Apart from that, it's inert. But the energy must be going somewhere.»

«OK.» Marcus walked up to a buttress, and switched his collar focus to scan the aperture. It was veiled by a grey haze, as if a sheet of fog had solidified across it. When he took another tentative step forward the fluid in his semicircular canals was suddenly affected by a very strange tidal force. His foot began to slip forwards and upwards. He threw himself backwards, and almost stumbled. Jorge and Karl just caught him in time.

«There's no artificial gravity underneath it,» he datavised. «But there's some kind of gravity field wrapped around it.» He paused. «No, that's not right. It pushed me.»

«Pushed?» Katherine hurried to his side. «Are you sure?»

«Yes.»

«My God.»

«What? Do you know what it is?»

«Possibly. Schutz, hang on to my arm, please.»

The cosmonik came forward and took her left arm. Katherine edged forward until she was almost under the lambent doughnut. She stretched up her right arm, holding out a sensor block, and tried to press it against the doughnut. It was as if she was trying to make two identical magnetic poles touch. The block couldn't get to within twenty centimetres of the surface, it kept slithering and sliding through the air. She held it as steady as she could, and datavised it to run an analysis of the doughnut's molecular structure.

The results made her back away.

«So?» Marcus asked.

«I'm not entirely sure it's even solid in any reference frame we understand. That surface could just be a boundary effect. There's no spectroscopic data at all, the sensor couldn't even detect an atomic structure in there, let alone valency bonds.»

«You mean it's a ring of energy?»

«Don't hold me to it, but I think that thing could be some kind of exotic matter.»

«Exotic in what sense, exactly?» Jorge asked.

«It has a negative energy density. And before you ask, that doesn't mean anti-gravity. Exotic matter only has one known use, to keep a wormhole open.»

«Jesus, that's a wormhole portal?» Marcus asked.

«It must be.»

«Any way of telling where it leads?»

«I can't give you an exact stellar coordinate; but I know where the other end has to emerge. The xenocs never called for a rescue ship, Marcus. They threaded a wormhole with exotic matter to stop it collapsing, and escaped down it. That is the entrance to a tunnel which leads right back to their homeworld.»

Schutz found Marcus in the passenger lounge in capsule C. He was floating centimetres above one of the flatchairs, with the lights down low.

The cosmonik touched his heels to a stikpad on the decking beside the lower hatch. «You really don't like being wrong, do you?»

«No, but I'm not sulking about it, either.» Marcus moulded a jaded grin. «I still think I'm right about the dish, but I don't know how the hell to prove it.»

«The wormhole portal is rather conclusive evidence.»

«Very tactful. It doesn't solve anything, actually. If they could open a wormhole straight back home, why did they build the dish? Like Katherine said, if you have an accident of that magnitude then you devote yourself completely to survival. Either they called for help, or they went home through the wormhole. They wouldn't do both.»

«Possibly it wasn't their dish, they were just here to investigate it.»

«Two ancient unknown xenoc races with FTL starship technology is pushing credibility. It also takes us back to the original problem: if the dish isn't a distress beacon, then what the hell was it built for?»

«I'm sure there will be an answer at some time.»

«I know, we're only a commercial trader's crew, with a very limited research capability. But we can still ask fundamental questions, like why have they kept the wormhole open for thirteen thousand years?»

«Because that's the way their technology works. They probably wouldn't consider it odd.»

«I'm not saying it shouldn't work for that long, I'm asking why their homeworld would bother maintaining a link to a chunk of derelict wreckage?»

«That is harder for logic to explain. The answer must lie in their psychology.»

«That's too much like a cop-out; you can't cry alien at everything you don't understand. But it does bring us to my final query. If you can open a wormhole with such accuracy across God knows how many light-years, why would you need a starship in the first place? What sort of psychology accounts for that?»

«All right, Marcus, you got me. Why?»

«I haven't got a clue. I've been reviewing all the file texts we have on wormholes, trying to find a solution which pulls all this together. And I can't do it. It's a complete paradox.»

«There's only one thing left, then, isn't there?»

Marcus turned to look at the hulking figure of the cosmonik. «What?»

«Go down the wormhole and ask them.»

«Yeah, maybe I will. Somebody has to go eventually. What does our dear Katherine have to say on that subject? Can we go inside it in our SII suits?»

«She's rigging up some sensors that she can shove through the interface. That grey sheet isn't a physical barrier. She's already pushed a length of conduit tubing through. It's some kind of pressure membrane, apparently, stops the ship's atmosphere from flooding into the wormhole.»

«Another billion-fuseodollar gadget. Jesus, this is getting too big for us, we're going to have to prioritize.» He datavised the flight computer, and issued a general order for everyone to assemble in capsule A's main lounge.

Karl was the last to arrive. The young systems engineer looked exhausted. He frowned when he caught sight of Marcus.

«I thought you were over in the xenoc ship.»

«No.»

«But you . . .» He rubbed his fingers against his temples. «Skip it.»