Raj pointed to the nearest mine-shaped object. Ewan took one glance, and then fired a stream of bullets towards it – perhaps in the hope of making a hole in the shield’s coordinate field or something. To Raj’s horror, the border point seemed to have its own miniature shield too.

There was a shriek on his right. Mark was physically holding Kate back as she screamed.

‘But destroying a computer won’t be enough,’ he continued, doing his best to sound brave. ‘You’ve got to wipe out all their research too. Get into their files and delete anything that mentions Atmospheric Metallurgic Excitation, and blow up their physical archives too. Do that, and they’ll have to start over. It could take years for them to get it right again. And don’t worry about here… I set fire to the library before I left it, and the fire should spread. I’m sorry, Ewan… but like you said, stop AME even if it means…’

‘You did the right thing, Raj,’ Ewan said. ‘Now find a way out.’

‘What, through the shield? Sorry Ewan, I’m screwed.’

Raj had noticed how casual Ewan’s voice sounded, like he was refusing to accept the hopelessness of the situation. Raj did not have that luxury: his dyslexia-driven ability to see to the core of a problem told him exactly what his situation was, and his ability to come up with off-the-wall unexpected ideas would have helped if there were any kind of way out. But Raj knew that searching for one would be like trying to avoid a one-move checkmate.

‘Dig underground,’ Ewan said, trying to hide his growing desperation. ‘Get to one of the grassy areas, and—’

‘The brains that came up with AME must have thought of someone tunnelling,’ said Raj, his first tears emerging. ‘And besides, how much time do you think I have? Reinforcements are minutes away.’

‘Then strip,’ said Jack in his usual matter-of-fact manner. ‘Leave your weapons, and remove any clothes that have traces of metal. We only need your body to get through.’

‘I’m sorry,’ Raj replied. ‘I had a spinal operation when I was twelve, remember? I told you when McCormick and Lorraine were arguing. There’s metal all down my back. Even if I were naked, the shield would blow my spine out.’

Kate finally got past Mark by punching his jaw and kneeing him in the groin. She reached Ewan and Jack and stared at her boyfriend through the invisible barrier that would cost him his life. And with her panic-stricken eyes gazing into his, she opened her mouth but no words came out.

Raj understood. He had absolutely no idea what to say to her either.

‘But actually,’ he breathed, ‘getting my spine blown out might be the best option.’

‘What the hell’s that supposed to mean?’ barked Ewan.

‘I mean not getting captured. You know why, Kate.’