With lives on the line and the prospect of a nuclear war, he needed to mitigate that risk. Jax had pulled up the prison blueprints supplied by Clarke before pressing the knock-up. And as well as having Turner scan the RF frequencies to the four doors he needed to open to gain access to Supermax, he’d also got him to scan a broom closet, a mains room and a plant room. He was now holding those three keys, ready to dive through the nearest door and take cover if he heard as much as a footfall.

With the three in-case-of-emergency FOBs unused, Jax breathed a little easier as he reached the entrance to Supermax, although, given where he was standing was also known as the Gates of Hell, he probably should have been hyperventilating.

He swapped the three electronic keys he had been holding for the four he had in his pocket. Then he looked down, picked out the key marked ‘D1’ – short for Door 1 – and waved it in front of the electronic pad. And . . . Open Sesame! . . . Supermax.

As per his training, Jax crouched and duckwalked his way through the open door. He had no reason to doubt Turner, and was sure he had done what he’d asked, but he nevertheless wanted to minimise his exposure to the guard’s box – which in Supermax was actually a round dome with a 360-degree view.

Jax turned, sat and put his back against the guard’s box when he arrived. Now would be the time to check his weapon – if he had one. Now would also be the time to call in his position, let his team know he was locked, loaded and ready to go. But he did not have a team. Not anymore. He was one-out and all alone.

He listened carefully but heard no movement. If Turner had not been successful, the mission was over. Jax couldn’t fight an armed man in his condition and win, no matter how skilled he was in hand-to-hand contact. He slowly moved towards the doorway into the dome, staying below the half-sphere of clear perspex the guard should be periodically gazing through to ensure all was in order. He rounded the final bend and closed in on the door.

He slowly stood up until his eyeline was level with the glass. Peering through, he could see a disposable coffee cup and a half-eaten sandwich on the desk. And, beyond them, the guard, slumped over the desk, having the deepest kip of his life.

Jax stood tall and exhaled, the butterflies that had been fluttering about in his stomach leaving with the spent breath. He looked down into his hand and pulled out the key marked ‘D2’. He walked over to the next door: blast-proof and four inches thick. Suddenly the butterflies were back, no longer fluttering, the winged creatures scratching and clawing as they rushed down his throat, stealing his air as they burrowed their way back to his belly.