‘Military intelligence. Johnny’s in human resources so in theory he has much higher-level security clearance than I do. This is a guy who’s on a team that can literally vet anybody.’

And so she had asked him to contact Johnny, all the while wondering why she was doing this. Was it for Alex? It wasn’t like she owed him anything, and in fact every sensible and settled-down fibre of her body told her that having anything further to do with Alex Abbott was very bad news indeed. He had all kinds of problems. He was a dangerous man. Dangerous literally and dangerous metaphorically.

And yet . . .

Johnny at RAF Chicksands would look into it, she was told. But a couple of days later her contact had been back in touch sounding somewhat discombobulated. ‘Who are these people?’

‘Um, I was hoping you could tell me.’

‘Well, no, I can’t. And nor can Johnny. According to him there are all kinds of clearances needed. Levels he didn’t even know existed. He says he’s leaving well alone and reckons you should, too.’

Which was enough to spook anyone.

She stopped, right there in the car park, halfway to her car, with something having occurred to her. The absence of something. The absence of a sound.

She swung about and sure enough, the door to the stairwell had not clicked shut. Either the mechanism was faulty or something on the other side was stopping it.

The man who had passed her? Had he remained there for some reason, preventing the door from shutting? From her position she could see that the door rested in the door frame, just not quite fully closing, although it was impossible to tell if there was anything – or anyone – on the other side.

Her mind went to something that Alex had told her once. Listen to your instinct. She swallowed. Her eyes went back to her car. Her keys were in her hand and she activated the clicker, although why, she wasn’t sure. The car unlocked with a comforting clunk. Sidelights came on. The internal light glowed. There was no sign of anybody there.

Or was there? Did she imagine it, or was there a movement in the shadows simultaneously accompanied by a shuffling sound? In the office it was occasionally joked that there were rats down here but somehow she didn’t think that was a rat.

Listen to your instinct.

Smartly, she turned, and although her first thought was to go back up the stairs into the sanctuary of her office, that door still had not shut, and so instead she headed quickly for a narrow pedestrian walkway to the left of the exit ramp, trotting up it fast towards the rectangle of daylight at the top.