‘You died in that world and you can never have those lives back. We cannot and will not ever return you and, once you know why you are here and fully understand the concept of timelines, you will agree you can never go back. Your presence would impact on hundreds, thousands, millions . . . countless tiny events in the history of humanity that could ultimately have devastating effects.’

Ben swallows, not comprehending and not absorbing the meaning of his words because understanding what Roland just said is not acceptable.

‘The three of you could take over this place,’ Roland says into the silence of the room. ‘You’re capable of doing that, but you have been very carefully chosen . . .’

‘What for?’ Safa asks in a voice choked and hoarse.

‘In twenty sixty-one a young scientist working alone made a breakthrough that enabled time travel to become possible. I do not know how it works. Nobody here knows how it works. It has something to do with a mathematical equation and that is the entirety of my knowledge surrounding how it works. Suffice to say, it does work. There is a device that enables time travel.’

‘Who made it?’ Safa asks.

‘Does it matter?’ Roland asks carefully. ‘This happened forty-one years after your death, Miss Patel. The inventor had no concept of security and because he or she never thought of the dangers, he or she never thought anyone else would either. The device became known,’ he continues bluntly. ‘The original has been secured but we know that another has been replicated and is now in use.’

‘How do you know?’ Ben asks.

‘Because the timeline of humanity has changed, Mr Ryder. The inventor went forward fifty years and made observations on society. Non-intrusive and non-affecting. Merely observations done as part of a series of tests determined to prove accuracy of the device. Later, when the inventor went back to that same point, it had changed.

‘The first trip fifty years in the future showed a society and species advancing as it should. The second trip, to the same point and location, revealed a post-apocalyptic wasteland. Cities in ruins—’

‘Maybe he got the date wrong.’

‘No, Mr Ryder. The date was not wrong. It was the same point in time at the same location previously used.’

‘How can you be so sure?’

‘The person invented time travel! I’m sure they could accurately record a date and location.’

‘Mistakes happen,’ Ben says. ‘People get things wrong all the time . . . write down a date wrong . . . attack a room full of German guards . . .’

‘I said sorry,’ Harry mutters.

‘My face still hurts,’ Ben says pointedly.

‘Be quiet,’ Harry rumbles. ‘The officer is speaking and I want to eat.’

‘I’m not an officer,’ Roland says into the stunned silence. ‘Are you taking this in, Mr Madden?’

‘Aye. Have you checked the Boche, sir? Sort of thing they’d do.’

‘Er,’ Roland says, clearly thrown off his train of thought.