She rolled over, gulping, a half-choke. A trail of thin vomit ran down her chin. She wore the expression of the torturer's victim, an utter incomprehension of how one person could do this to another. Frightened eyes found her left hand. She drew it up to her face, mesmerised, and began to cry.

"Gabriel?"

She was curling up into a foetal ball, sucking down air in shallow gulps.

"Gabriel, did the cortical node work?"

"Yes."

"Gabriel, you have to get up."

A shiver ran down her spine. "I want to go home," she whispered through clenched teeth.

"We are going home. Now get up."

Gabriel rocked back on to her knees, cradling her left hand. Tears streaked her cheeks. "Oh, Christ, Greg."

"I know," he said. "Now look round and find something you can use as a club."

"No. No, I can't do that. Don't make me do that. Please, Greg. Please."

"You can't leave me here." Greg deliberately let a note of desperation filter into his voice. Bullying her with guilt. "There's only about thirty minutes left before the tower blows."

She clambered to her feet in slow-motion stages, never allowing her arm to leave her side. He could see the film of sweat on her forehead, and felt clammy apprehension rise. The grisly snap of cracking bone seemed to be echoing around the room.

She tottered off behind him, rummaging through the stacks of food crates. He didn't look, keeping still, eyes on the ancient worn brickwork on the other side of the stairs.

"Will this do?" she asked. She couldn't think for herself. Shock numbness had set in.

The length of wood she'd found was a metre long, four or five centimetres wide. Three rusty screws jutted out of the middle. It ought to be heavy enough, he thought.

"It'll do." With grim horror he realised that after she'd smashed his hand, he'd have to yank it free through the handcuff himself. She could never manage that.

"Gabriel, you must be hard. Swing the club real hard, no messing. Imagine it's Armstrong's hand, or something. Don't do it to me twice. Promise?"

"Right."

He put his left hand on the ledge of wood, then instructed his cortical node to disengage the nerves of his left arm. From the elbow down he could feel nothing, not even the dead-meat coldness of anaesthetic, the buoyant release of morphine. His forearm and hand had ceased to exist.

"OK," he said, finding out just how much it'd cost Gabriel to say that.

Gabriel pushed the handkerchief into his mouth. It was disgusting. Soggy, tasting of sour acidic stomach juices. Good. Focus on the revulsion. Shutting out the sight of Gabriel steadying herself on the second step. Knuckles whitening as she clenched the makeshift club. Her face mimicking the intense concentration he'd once seen on a golf pro's face as he lined up his putter for an albatross.

Greg heard the swish of air.