There was a door set into the reactor side, just big enough for a human or a Polypheme to squeeze through. Darya cracked it open. When the Zardalu did not protest or back away she swung it wide.

The chamber inside was a kind of buffer zone, with a second closed door at its far end. It was the area where decontamination would take place, after a maintenance engineer, presumably wearing suitably heavy protection, had finished work and emerged from the interior.

She gestured to the Zardalu. “Put him in there.”

The space was only just big enough for Dulcimer, tightly coiled as he was. Darya squeezed the door shut on the inert Polypheme and felt guilty. If she understood the mechanism, the fail-safe would allow the outer door to be opened only when the inner door was closed. But the inner door could be kept open from outside the whole unit. That meant that until Darya closed the interior door, Dulcimer would not be able to escape even if he wanted to.

She crossed her fingers mentally and moved the control of the inside door. Dulcimer was now exposed to whatever sleet of radiation came from inside the reactor. And since Darya knew nothing of its design, she had no idea how much that might be.

How long dare she leave him inside? A few minutes might be enough to kill. Too much would be worse than too little. The Zardalu just stood watching. They must assume that she knew what she was doing. Darya was in an agony of worry and guilt.

“May I speak?” It was E.C. Tally, interrupting at the worst possible moment. J’merlia was standing by his side, fully awake again.

“No. Keep quiet, E.C. I’m busy.”

“With respect, Professor Lang,” J’merlia said, “I think you will find it of advantage to listen to his thinking.”

“I am still wondering,” Tally went on without waiting for Darya’s reaction, while she glared at both of them, “why you requested that I ask the Zardalu about the ways out of here.”

Darya rounded on him. “Why do you think? Do you two like it here so much you want to stay forever? You will, you know, unless you do more than just sit around.”

She knew that Tally did not deserve the outburst, but she was ready to be angry with anyone.

He nodded calmly. “I understand your desire to leave, and quickly. But that does not address my question. Your request still confuses me, since we know where we were taken as we came here. I have all that information recorded in memory. And thus we already know how to get to the surface, without asking anyone.”

Darya had a few moments of wild hope before logic intruded. “That won’t do, E.C. I believe that you remember exactly the way you came, and you could probably backtrack. But the first part of the trip was underwater — I saw you go before I did. And the sea around that whole area is swarming with Zardalu. Even if we escaped all the way back that far, we’d be caught in the water before we ever got close to land.”

“True. But may I speak? I am aware that escape through water is infeasible, and I would not propose that.”

“Then what the devil do you propose?” The collapse of even the faintest hope made Darya angrier than ever. “Tunneling up through solid rock? Eating your way out?”

“I would propose that we retrace our downward path until we reach the first set of air pumps. And we then seek to follow their flow path directly to the surface.”

Air pumps. Darya was angrier than ever — at herself. She had felt the breeze of dry fresh air and heard the chugging rhythm of pumps in the very first chamber that she had been taken to. There must be hundreds of others, riddled through the whole labyrinth of chambers. All logic said that the ducts must terminate on the surface of Genizee.

“Tally, I’ll never say anything bad about embodied computers again. You can think rings around me. Bring that Zardalu over here, would you? — the bigger one. Quick as you can.”

He hurried away, and she glanced at the closed reactor door while he was whistling at their captor. In her preoccupation with Tally and J’merlia she had forgotten all about Dulcimer. For all she knew, he could be cooked right through and dead. She was reassured by a sudden sound — a loud Boom! Boom! Boom! from inside. She closed the inner door, but held the outer one closed as the bigger Zardalu approached.

“Tell it, E.C.,” she said. “Tell it to go right now and bring the senior Zardalu, the one that I was talking to earlier. Say I am ready to cooperate fully on the terms outlined to us, but I won’t deal with anyone else. And both of you — get ready to move fast.”

The hammering on the door of the reactor chamber was getting steadily louder, together with a muffled screaming sound from within. Darya held the tag closed, waiting and waiting while the Zardalu dithered around as though unable to agree to the terms that Tally was explaining to it. At last it headed for the exit, pausing on the threshold for a final whistling exchange with the guard who would be left behind. That Zardalu moved closer, to dangle three brawny tentacles menacingly above Darya, J’merlia, and E.C. Tally.

Darya waited thirty more endless seconds, until the other Zardalu should be well out of the way. Then she took a deep breath and unlocked the outer door. She was ready to swing it open, hoping that luck had been on her side and the Chism Polypheme had received the perfect dose of radiation.

“Come on out, Dulcimer.”

She did not have a chance to open anything. The door was smashed out of her hands and whirled round to clang against the reactor wall.

Dulcimer came out. Or something did.

What had entered was a squat cucumber-mass, silent and sullen. What emerged was an extended nine-foot squirt of luminous apple green, screaming at the top of its single lung.

The remaining Zardalu was right in the line of flight. Dulcimer knocked it flat and did not even change direction.

“Dulcimer!” Darya cried. Talk about an overdose! “This way. Follow us — we’ve got to reach the air pumps. Dulcimer, can you hear me?”

“Whooo-ooo-eee!” Dulcimer hooted. He went zipping around the whole chamber, bouncing from wall to wall and propelled by mighty spasms of his spiral tail.

“Run for it!” Darya pointed E.C. Tally and J’merlia to the chamber exit and scrambled after them, her eyes still on Dulcimer. The Zardalu, groggy but still active, was back upright in a thresh of furious tentacles. It grabbed for the Polypheme as he flew by, but could not hold him. He bounced off the reactor, paused by the door for a second as though tempted to enter again, and then sprang up to the ceiling. In midair he turned upside down and went hurtling off at a different angle.

“Dulcimer!” Darya cried again. She had been dawdling, and the Zardalu was starting in her direction. She could not wait any longer. “Go to the air pumps.”

“To the intake,” J’merlia called, suddenly at Darya’s side. “Quickly. It is farther along this tunnel.”

As J’merlia spoke, Dulcimer came whizzing past them, straight as an arrow down the corridor. Darya gasped with relief and ran the same way. She came to the great nozzles of the air pumps — and then realized that Dulcimer had flown right on past them. He had vanished into another and wider air duct, far along the corridor. Darya heard the cackling scream fading away in the distance. And then she could not hear it at all.

“Inside,” Tally called. He was far beyond the air-duct entrance. “If you climb a few meters farther, the tentacles will not be able to reach you. And this duct is too narrow to admit a Zardalu!”

“Wait a second. J’merlia is still back there.” Darya was worming feetfirst into the straight section of pipe, raising her head as she pushed in deeper. Progress was slow, and the Zardalu was closing fast — too fast. She could never get out of range in time.

But J’merlia was between Darya and the Zardalu, and he was making no attempt to reach the air duct. Instead he ran off to the side, drawing the Zardalu after him. He disappeared from Darya’s narrow field of view, ducking a swipe from a thick tentacle.