But why would Mills place the key inside Seiger and Sten notepaper if it wasn’t for Seiger and Sten? And if the key didn’t open the office, what did it open?

I tried to look through the front window, but all I could see was the vague shape of a long desk, and the curve of a sofa on the left. As I stepped back, I felt my wallet shift against my leg and knew that, inside one of the zip pockets, were my picks. I looked again at the door: it was big, heavy, and would be hard, maybe impossible, to break open with physical force. The lock was different, though. It was just a pin tumbler. I could get past that.

But now I was doubting myself.

The key didn’t fit, so what if the alarm code Mills had given me didn’t work either?

I looked at the door, at the piece of paper in my hands with 459822 written in the middle. I thought about Black Gale, about the nine people who’d called it home.

There was only one way to find out.

I dropped to my haunches at the door and pulled on a pair of latex gloves. The wind died, the place becoming quiet again, except for the perpetual lap of water in the drains, and babble of the gutters.

Thirty seconds later, something clicked and the door had come away from its frame.

Straight away, the security system started to chirp.

As quickly as possible, I moved inside the building – leaving the door open in case I needed a rapid escape – and searched for the alarm box. About five feet from me, on a wall adjacent to the front desk, its fascia was blinking with blue lights. It was near black inside the office but the lights produced an intermittent wash, enough for me to see that the alarm box had a small, flip-down section housing the number pad. I pulled it open and punched in the code. For a split second, nothing happened: the LEDs were still winking, the sound hadn’t stopped.

I turned to the door, ready to run.

But then everything snapped to silence.

39

I clicked the main door shut, and everything retreated into darkness. I could just about make out the reception desk, a curved piece of pale wood – built on to a slight platform – and a sofa and a couple of tub chairs.