Silvia was discussing the choice of food with a companion, and as Dallen drew near he saw that, although slightly pale, she looked as though she had recovered from her period of trauma. He took in the firm-jawed face and the prominence of the lower lip, the massy fullness of breasts emphasised by the flatness of abdomen, the air of easy strength combined with femininity, and inside him was born a pain which had something to do with the fact that he had never read poetry and therefore did not have access to the words needed to let Silvia know how he felt about her. He was hesitating, overwhelmed, when she looked in his direction. She carried on her conversation without the slightest break, but her eyes engaged Dallen's and remained there, unwavering, while he moved towards another row of machines.

He smiled at her, then developed the conviction it was the same meaningless facial grimace he had made earlier on meeting Mathieu, and deliberately broke the visual contact by moving behind a drinks dispenser. Freed of the intense emotional pull, he selected food for Cona and himself, and when he emerged from an alley of cabinets Silvia was gone.

A few minutes later, back in his cabin, he found Cona sitting on the edge of her bed, blinking drowsily. Her smock had ridden up to her broadening hips, exposing a wisp of colourless hair at the juncture of puckered thighs. He twitched the hem of the garment down to her knees and began setting out dishes of food on the foldaway table. The air smelted of stale perspiration.

"Din," Cona mouthed with effort. "Di-in."

"Very good," Dallen said, blanking out his freshly renewed mental image of Silvia's face. "Say dinner.

"Dm," Cona shouted in sudden manic joviality, lurching towards the table. She picked up a spoon, holding it sideways in her fist, and reached for a dish of chocolate mousse. Dallen had found that if he gave in and permitted her to eat some dessert at the beginning of a meal it was then quite easy to coax her into having a fair amount of the main protein dish, but all at once the idea was intolerable.

Without speaking, he closed his hand over Cona's and steered the spoon towards a block of moulded salad. She froze for a moment, then began to resist with her considerable strength. Before he quite knew what he was doing, he had half-risen to his feet to gain leverage and had clamped Cona's head against his hip. Subduing her with furious ease, he forced her to take salad on to the spoon and was guiding it to her mouth when something prompted him to glance towards a mirrored wall at the for side of the room.

The tableau he saw there, with its ancient formalised composition — oppressor looming over the oppressed — could have been from any period in history. The medium could have been grainy 20th Century or age-darkened oil paint or perspective less woodcut, but the principal elements were the same. Faces of torturer and victim alike — both robbed of all humanity — turned towards the camera-artist as though demanding to go on record for posterity, Dallen released his wife at once and stood facing his reflection. "Bastard," he whispered. "The bastard has to pay."

As a preliminary to the execution Dallen kept a close watch on Mathieu's movements.

He was quickly rewarded by the discovery that Mathieu, even when he had a freedom of choice, preferred a fixed pattern of activity. The work schedule called for each person in Renard's team to be responsible for two adjacent stacks of grass trays, the most tedious task being the rotation of the sunlight panels to give a reasonable simulation of night and day. Each tray also had to be lightly watered at some time during its "night" period. There was no hard-and-fast rule about exactly when the watering should be carried out, but Mathieu liked to do it as soon as he had removed each sunlight panel, starting at the top of the stacks and methodically working down to deck level. Every morning at eleven, ship time, he climbed a twenty-metre alloy ladder attached to the front of one stack and serviced its top layer of trays. That done, he stretched all the way across the aisle and worked on his other stack from its rear, taking advantage of his long reach to avoid making two separate ascents. It was a technique of which Renard did not approve, but he had contented himself by sourly reminding Mathieu he was not covered by industrial insurance. And Dallen had listened to that particular exchange with satisfaction, knowing it would help smooth his way through what was to follow…

On the fifth morning of the voyage he awoke early. Cona was snoring peacefully in her bed at the other side of the prefab, and Mikel was fast asleep in his cot, one foot projecting through the bars. There was little in the peaceful tallowy dimness of the cabin to indicate that it was part of an engineered structure which was hurtling through distorted geometries of space. Were it not for near-subliminal, amniotic fluttering in the air Dallen could have believed himself to be in a holiday chalet anywhere on Earth or Orbitsville. His thoughts turned at once to Silvia London, only a few paces and partitions away on the same deck, but he hurriedly blanked out a vision of how she might look in bed. His morning erections were becoming painfully insistent, and on this crucial day all his mental and physical energies had to be directed elsewhere.

He quietly got out of bed and took stock of his emotions, trying to ascertain how he felt about his decision to proceed immediately with Mathieu's execution. There was a certain sense of disbelief mingled with a cold sadness and fears for his own safety — but the bask resolution was still there, intact, a dominating force which excluded compassion or regrets.

That's all right, he thought, unaccountably relieved. Nothing has changed.

Taking care not to disturb Cona or Mikel, he used the radiation shower cubicle — wishing it could have been a stinging water spray — and got dressed in the soft shirt and slacks which were his usual working attire. He brought the travel bag out of a closet and took from it the small container of special paint, which he put in his breast pocket.

There was nobody else abroad on Deck 5 when he left his cabin, so we went straight to the tubular elevator cage, dropped himself to the bottom of the cargo hold and stepped out into an angular jungle of scaffolding. Tall stacks of grass trays, half of them glowing under artificial sunlight, created a three-dimensional confusion of brilliance and shadow. There were puddles on the floor and the air was warm and humid, rich with meadow scents, dulling metal surfaces with condensation.

It took Dallen less than a minute to make sure no others had showed up early for work, then he went to Mathieu's two stacks and climbed the innermost ladder, the one always used by Mathieu. At the top, precisely when it was necessary for him to be alert and at peak efficiency, he was numbed by an awareness that he was at the point of maximum danger. He was only a few metres below the ring-shaped Deck 5, in a position readily visible to anyone who might emerge from a passenger cabin, and now his scheme — so foolproof when evaluated in the security of his bed — seemed reckless beyond belief.

With a final swinging glance at the circular guard rail above, he took the paint container out of his shirt pocket and sprayed a colourless fluid on to the ladder's top rung. Highly nervous, fighting off a tendency to shake, he returned the container to his pocket and slid commando-fashion to the foot of the ladder. The greenhouse stillness of the bottom deck was heavy and undisturbed. Dallen ran to the elevator, took it up to Deck 5 and within a matter of seconds was back in the sanctuary of his cabin, where Cona and Mikel were still asleep. The entire sortie had taken approximately three minutes.