‘Well, I grew up eating my greens and not smoking,’ said Alex. ‘My life expectancy’s probably still in its eighties.’

‘Be sensible, Alex. And your life expectancy will be a lot lower if you’re planning to go off on your own again—’

‘Alright. I vote Kate.’

She sat up straight, alarmed.

‘Why?’ she asked.

‘Because Ewan will have half of New London after him, and I’m screwed the moment they realise I’m not a clone. I’m guessing McCormick wants the volunteer to hold on to the detonator and only use it when absolutely necessary, and let’s face it – you’re the most careful one of us.’

‘No,’ said McCormick, ‘I don’t want Kate holding this.’

Kate gasped, conflicting thoughts fighting inside her mind. On the one hand, a scary responsibility would no longer be hers. On the other, why the hell would McCormick deny her the opportunity? The man had spent his whole life using responsibility as a tool to build up young people, so it seemed out of character for him.

‘Why not?’ she asked, a little too loud.

‘Because you might end up having to use it. Just trust me.’

‘I vote Kate too,’ said Ewan.

Kate began to wonder whether she was truly opposed to the responsibility. Her friends’ encouragement seemed to be changing her mind. And at her side, McCormick’s resistance was fading.

‘I’ll be giving you the most powerful explosive device this war has ever known,’ he said weakly.

‘It’s a good job you trust me then, isn’t it?’

McCormick let out a long sigh: the kind of sigh people resorted to when they knew they were beaten.

‘If our situation becomes unsalvageable,’ he said, ‘I’ll give you the six-digit code. Ideally, this won’t happen. The plan is to get inside, destroy the shield’s control system, wipe out every single bit of research down to the last Post-it Note, and – if possible – get out and go home—’

‘Wherever home ends up being,’ said Alex.

‘Get out and go home… and if we can do all that without needing a big explosion, we’ll save this weapon for another time. You’ll give me the detonator back and we’ll never speak of this again. But if I do give you the code – if our strike goes so badly that we need to take this kind of action – you must follow my instructions to the letter. Because this is the one weapon in our arsenal that we absolutely can’t afford to waste.’

‘OK,’ muttered Kate, ‘I get it.’

McCormick nodded and sighed as he tucked the detonator back into the rucksack.

‘When we get inside,’ he finished, ‘take it out of here, and look after it well.’