I’d read about these hidden rooms in a magazine article quite recently. Although they were as old as the hills, they were now in vogue and becoming a common feature in large homes across London.

My interest piqued as I stepped towards it and saw that inside it was more like a really big cupboard than a proper room. However, there was space enough for a desk with a chair and book shelves on all three sides.

There was a computer on the desk and the sight of it caused the air to lock in my chest.

This one obviously hadn’t been discovered during the police search. And there had been no mention in the report of a secret room.

I realised suddenly why Carver had become panicky just now when I’d said I was going to look around the house. He’d left the door to his secret room open, no doubt because he’d been working in there before going out for some fags.

As I stepped inside I wondered if I had stumbled onto something significant. Was it from this tiny cubbyhole that Carver had sent out the threatening text messages?

I looked at the computer keyboard and screen, then reached out and touched the mouse to see if it had been left on. When the screen came to life I couldn’t believe my luck.

I sat on the chair with a view to delving into his files. But first I studied the icons on the desktop, and noted he was using Google Chrome as a browser. I thought that would be a good place to start.

I went straight to the history list to see what Carver had been looking up online. There’d been surprisingly little activity over the past couple of days. But five days ago – on the Tuesday – he’d searched for information on someone known as La Asesina.

As soon as I opened up the first site he’d visited I saw that La Asesina was the name that had been given to a woman who was reckoned to be among the most ruthless assassins in Mexico. The English translation was The Slayer.

And instinct told me that she was the same woman who had crossed the Atlantic in order to bring terror to London.

65

Rosa

They were still in the pub when they heard the sirens.

‘It sounds like there’s something going on close by,’ Alice said.

When they left the pub they saw that a small crowd had gathered on the walkway. The street where the cop lay dead in her patrol car had been cordoned off. Two other police cars were parked next to it, and there were lots of officers around in high visibility jackets.

‘I wonder what’s happened,’ Rosa said, and then added, ‘I think it’s probably best that we don’t hang around.’