Kirsty was looking down, too. Johnny could see other shapes on the floor in the shadows.

‘He’s been killing Sc— people,’ he whispered.

Shoot them in space, shoot them on a screen, and there was just an explosion and five points on the score total. When they’d been shot from a few metres away, then there was simply a reminder that someone who had been alive was now, very definitely, not alive any more. And would never be again.

He looked up at the Gunnery Officer. ScreeWee were cold-blooded and a long way from being human, but this one had a look about it – about him – that suggested a mind running off into madness.

There was a silvery sheen on his scales. Johnny found himself wondering if the ScreeWee changed colour, like chameleons. The Captain had always looked more golden when she was acting normally, and became almost yellow when she was worried . . .

She was the colour of lemons now.

She hissed something. The guards looked at her in surprise, but turned and filed obediently out of the bridge. Then she turned to the Gunnery Officer.

‘You killed all of them?’ she said, softly.

‘They tried to stop me! It is a matter of honour!’

‘Yes, yes. I can see that,’ said the Captain, in a level voice. She was shifting position slightly now, moving away from the humans.

‘A ScreeWee dies fighting or not at all!’ shouted the Gunnery Officer.

The Captain’s scales had faded to the colour of old paper.

‘Yes, I understand, I understand,’ she said. ‘And the humans understand too, don’t you.’

The Gunnery Officer turned his head. The Captain spread her arms, opened her mouth and leapt. The male must have sensed her; he turned, claws whirring through the air.

Johnny reached out and caught Kirsty’s gun as she raised it.

‘No! You might hit her!’

‘Why’d she do that? I could easily have shot him! So could the guards! Why just jump at him like that?’

The fighters were a whirling ball of claws and tails.

‘It’s personal. I think she hates him too much,’ he said. ‘But look at the screen!’

There were more green dots. Red figures that might have meant something to a ScreeWee were scrolling up on one side too fast for a human to read.

He looked down at the controls.

‘They’re getting closer! We’ve got to do something.’

Kirsty stared at the controls too. The seats were made to fit a ScreeWee. So were the controls themselves.

‘Well, do you know what means?’ she said. ‘Fast? Slow? Fire? The cigarette lighter?’

The fighters had broken apart and were circling each other, hissing. The green and red light from the screen threw unpleasant shadows.

Neither ScreeWee was paying the humans the least attention. They couldn’t afford to. ScreeWee walked like ducks and looked like a cartoon of a crocodile, but they fought like cats – it was mainly watching and snarling with short, terrible blurs of attack and defence.