Finally the wire cage dropped with a muted chime onto a bed of springs. The vibrations of the bell ebbed into the silence. After a minute the door to the shaft snapped open and the box of larvae was yanked brusquely into a harsh light.

There were no windows in the long white room, only incandescent gasjets. Every cranny of the room was visible in its sterility. No dust, no dirt invaded here. The cleanliness was hard and aggressive.

All around the perimeter of the room, white-coated figures were huddled in obscure tasks.

It was one of those bright, hidden figures who untied the box’s string and read the invoice. She gently opened the box and peered inside.

She picked up the cardboard box and carried it at arms’ length through the room. At the far end one of her colleagues, a thin cactacae with his spines carefully secured beneath thick white coveralls, had opened the large bolted door for which she was heading. She showed him her security clearance and he stood aside to let her precede him.

They walked carefully down a corridor as white and sparse as the room from which they had come, with a large iron grille at the far end. The cactus saw that his colleague was carrying something gingerly in both hands, and he reached past her and fed a programme card into an input slot in the wall. The slatted gate slid open.

They entered a vast dark chamber.

Its ceiling and its walls were far enough away to be invisible. Weird wails and lowing sounded distantly from all sides. As their eyes adjusted, cages walled with dark wood or iron or reinforced glass loomed at them irregularly in the enormous hall. Some were huge, the size of rooms: others were no larger than a book. All were raised like cabinets in a museum, with charts and books of information slotted before them. White-clad scientists moved through the maze between the blocks of glass like spirits in a ruin, taking notes, observing, pacifying and tormenting the cages’ inhabitants.

Captive things sniffed and grunted and sang and shifted unreally in their dim prisons.

The cactus walked briskly off into the distance and disappeared. The woman carrying the grubs made her way carefully through the room.

Things lunged at her as she walked past and she shuddered with the glass. Something swirled oleaginously through a huge vat of liquid mud: she saw toothy tentacles slapping at her and scouring the tank. She was bathed in hypnotic organic lights. She passed a small cage smothered in black cloth, with warning signs plastered ostentatiously on all sides and instructions on how to deal with the contents. Her colleagues drifted up to her and away again with clipboards and children’s coloured bricks and slabs of putrefying meat.

Ahead, temporary black wooden walls twenty feet high had been thrown up, surrounding a floor-space forty feet square. Even a corrugated iron ceiling had been hammered over the top. At the padlocked entrance to the room-within-a-room stood a white-suited guard, his head braced to take the weight of a bizarre helmet. He carried a flintlock rifle and a back-slung scimitar. At his feet were several more helmets like his.

She nodded to the guard and indicated her desire to enter. He looked at the identification around her neck.

“You know what to do, then?” he asked quietly.

She nodded and put the box carefully on the floor for a moment, after testing that the string was still tight. Then she picked up one of the helmets by the guard’s feet and slipped the unwieldy thing over her head.

It was a cage of brass pipes and screws that slotted around her skull, with one small mirror suspended a foot and a half in front of each of her eyes. She adjusted the chinstrap to keep the heavy contraption steady, then turned her back on the guard and fiddled with the mirrors. She angled them on their swivelling joints until she could see him clearly directly behind her. She switched focus from eye to eye, testing the visibility.

She nodded.

“All right, I’m ready,” she said, and picked up the box, untying it as she did so. She stared intently into the mirrors while the guard unlocked the door behind her. When he opened it he averted his eyes from the interior.

The scientist used her mirrors to walk backwards quickly into the dark room.

She was sweating as she saw the door close in front of her face. She switched her attention again to the mirrors, moved her head slowly from side to side to take in what was behind her.

There was a huge cage of thick black bars filling almost the whole space. From the dark brown light of burning oil and candles she could make out the desultory, dying vegetation and small trees that filled the cage. The gently rotting growth and the darkness in the room were thick enough that she could not see the far side of the room.

She scanned quickly in the mirrors. Nothing was moving.

She backed quickly up to the cage, to where a small tray slotted back and forth through the bars. She reached behind her and tilted her head up such that the mirrors angled down and she could see her hand groping. It was a difficult, inelegant manoeuvre, but she managed to grip the handle and tug the tray out towards her.

She heard a heavy beating in the corner of the cage, like thick rugs being slammed quickly together. Her breath came faster and she fumbled to pour the grubs onto the tray. The four little undulating lozenges slipped in a shower of paper debris onto the metal.

Immediately, something changed in the quality of the air. The caterpillars could smell the inhabitant of the cage, and they were crying out to it for succour.

The thing in the cage was answering.

These cries were not audible. They vibrated in wavelengths other than sonar. The scientist felt the hair all over her body bristle as the ghosts of emotions fleeted through her skull like half-heard rumours. Snippets of alien joy and inhuman terror wafted in her nostrils and ears and behind her eyes, synaesthetically.

With trembling fingers she pushed the tray into the cage.

As she stepped away from the bars, something stroked her leg with a lascivious flourish. She gave a moaning grunt of fear and yanked her trouser out of reach, clamped down on her terror, resisted the instinct to look behind her.

In her head-mounted mirrors, she glimpsed dark brown limbs uncurling in the rough undergrowth, the yellowing bone of teeth, black ocular pits. The ferns and scrub rustled and the thing was gone.

The scientist knocked brusquely on the door as she swallowed, holding her breath until it was opened and she stumbled out nearly into the arms of the guard. She snatched at the clasps under her head, pulling herself free of the helmet. She stared intently away from the guard while she heard him closing and locking the door.

“Is it done?” she whispered eventually.

“Yes.”

She turned back slowly. She could not look up, but kept her eyes firmly on the floor, checking that he told the truth by looking at the base of the door, then slowly and with a rush of relief raising her line of sight to eye-level.

She handed the helmet back to the guard.

“Thanks,” she murmured.

“Was it all right?” he asked.

“Never,” she snapped, and turned.

Behind her, she thought she heard a massive fluttering through the wooden walls.

She walked briskly back through the chamber of strange animals, realizing halfway through that she still clutched the now-empty box in which the grubs had come. She folded it and put it in her pocket.

She pulled the telescoping gate closed behind her on the massive chamber full of shadowy, violent shapes. She returned the length of the scrubbed white corridor and at last back into the Research amp; Development antechamber, through the first heavy door.