He was about to step forward when something made him look over his shoulder.

Running straight towards him along the outcropping, head down, hands almost touching the ground, was an enormous ratlike creature. Every ten or fifteen yards it paused for a moment, and looked out at the chalets, and Larsen caught a glimpse of its face, insane and terrified, another replica of his own.

‘Larsen! Larsen!’

Bayliss stood by the chalet, waving out at the desert.

Larsen glanced back at the phantom hurtling towards him, now only thirty feet away, then jumped up and lurched helplessly across to Bayliss.

Bayliss caught him firmly with his hands. ‘Larsen, what’s the matter with you? Are you having an attack?’

Larsen gestured at the figures around him. ‘Stop them, Bayliss, for God’s sake,’ he gasped. ‘I can’t get away from them.’

Bayliss shook him roughly. ‘You can see more than one? Where are they? Show me.’

Larsen pointed at the two figures hovering luminously near the chalet, then waved limply in the direction of the desert. ‘By the garage, and over there along the wall. There’s another hiding along that ridge.’

Bayliss seized him by the arm. ‘Come on, man, you’ve got to face up to them, it’s no use running.’ He tried to drag Larsen towards the garage, but Larsen slipped down on to the concrete.

‘I can’t, Bayliss, believe me. There’s a gun in my letterbox. Get it for me. It’s the only way.’

Bayliss hesitated, looking down at Larsen. ‘All right. Try to hold on.’

Larsen pointed to the far corner of Bayliss’s chalet. ‘I’ll wait over there for you.’

As Bayliss ran off he hobbled towards the corner. Halfway there he tripped across the remains of a ladder lying on the ground and twisted his right ankle between two of the rungs.

Clasping his foot, he sat down just as Bayliss appeared between the chalets, the revolver in his hand. He looked around for Larsen, who cleared his throat to call him.

Before he could open his mouth he saw the double who had followed him along the ridge leap up from behind the drum and stumble up to Bayliss across the concrete floor. He was dishevelled and exhausted, jacket almost off his shoulders, the tie knot under one ear. The image was still pursuing him, dogging his footsteps like an obsessed shadow.

Larsen tried to call to Bayliss again, but something he saw choked the voice in his throat.

Bayliss was looking at his double.

Larsen stood up, feeling a sudden premonition of terror. He tried to wave to Bayliss, but the latter was watching the double intently as it pointed to the figures near by, nodding to it in apparent agreement.

‘Bayliss!’

The shot drowned his cry. Bayliss had fired somewhere between the garages, and the echo of the shot bounded among the chalets. The double was still beside him, pointing in all directions. Bayliss raised the revolver and fired again. The sound slammed across the concrete, making Larsen feel stunned and sick.

Now Bayliss too was seeing simultaneous images, not of himself but of Larsen, on whom his mind had been focusing for the past weeks. A repetition of Larsen stumbling over to him and pointing at the phantoms was being repeated in Bayliss’s mind, at the exact moment when he had returned with the revolver and was searching for a target.

Larsen started to crawl away, trying to reach the corner. A third shot roared through the air, the flash reflected in the bathroom window.

He had almost reached the corner when he heard Bayliss shout. Leaning one hand against the wall, he looked back.

Mouth open, Bayliss was staring wildly at him, the revolver clenched like a bomb in his hand. Beside him the bluesuited figure stood quietly, straightening its tie. At last Bayliss had realized he could see two images of Larsen, one beside him, the other twenty feet away against the chalet.

But how was he to know which was the real Larsen?

Staring at Larsen, he seemed unable to decide.

Then the double by his shoulder raised one arm and pointed at Larsen, towards the corner wall to which he himself had pointed a minute earlier.

Larsen tried to shout, then hurled himself at the wall and pulled himself along it. Behind him Bayliss’s feet came thudding across the concrete.

He heard only the first of the three shots.

Chronopolis

His trial had been fixed for the next day. Exactly when, of course, neither Newman nor anyone else knew. Probably it would be during the afternoon, when the principals concerned — judge, jury and prosecutor — managed to converge on the same courtroom at the same time. With luck his defence attorney might also appear at the right moment, though the case was such an open and shut one that Newman hardly expected him to bother — besides, transport to and from the old penal complex was notoriously difficult, involved endless waiting in the grimy depot below the prison walls.

Newman had passed the time usefully. Luckily, his cell faced south and sunlight traversed it for most of the day. He divided its arc into ten equal segments, the effective daylight hours, marking the intervals with a wedge of mortar prised from the window ledge. Each segment he further subdivided into twelve smaller units.

Immediately he had a working timepiece, accurate to within virtually a minute (the final subdivision into fifths he made mentally). The sweep of white notches, curving down one wall, across the floor and metal bedstead, and up the other wall, would have been recognizable to anyone who stood with his back to the window, but no one ever did. Anyway, the guards were too stupid to understand, and the sundial had given Newman a tremendous advantage over them. Most of the time, when he wasn’t recalibrating the dial, he would press against the grille, keeping an eye on the orderly room.

‘Brocken!’ he would shout out at 7.15, as the shadow line hit the first interval. ‘Morning inspection! On your feet, man!’ The sergeant would come stumbling out of his bunk in a sweat, cursing the other warders as the reveille bell split the air.

Later, Newman sang out the other events on the daily roster: roll-call, cell fatigues, breakfast, exercise and so on round to the evening roll just before dusk. Brocken regularly won the block merit for the best-run cell deck and he relied on Newman to programme the day for him, anticipate the next item on the roster and warn him if anything went on for too long — in some of the other blocks fatigues were usually over in three minutes while breakfast or exercise could go on for hours, none of the warders knowing when to stop, the prisoners insisting that they had only just begun.

Brocken never inquired how Newman organized everything so exactly; once or twice a week, when it rained or was overcast, Newman would be strangely silent, and the resulting confusion reminded the sergeant forcefully of the merits of co-operation. Newman was kept in cell privileges and all the cigarettes he needed. It was a shame that a date for the trial had finally been named.

Newman, too, was sorry. Most of his research so far had been inconclusive. Primarily his problem was that, given a northward-facing cell for the bulk of his sentence, the task of estimating the time might become impossible. The inclination of the shadows in the exercise yards or across the towers and walls provided too blunt a reading. Calibration would have to be visual; an optical instrument would soon be discovered.

What he needed was an internal timepiece, an unconsciously operating psychic mechanism regulated, say, by his pulse or respiratory rhythms. He had tried to train his time sense, running an elaborate series of tests to estimate its minimum inbuilt error, and this had been disappointingly large. The chances of conditioning an accurate reflex seemed slim.