The time was just after eleven o’clock. She’d slept late partly because of the jet lag, but mostly because she’d sat up until the early hours preparing for her mission.

There was a lot to do in a short space of time. But she was used to working quickly. More often than not she was expected to carry out hits with barely twenty-four hours’ notice.

She had gone through the list that Roy Slack had given her and checked the website containing the photographs of most of the targets. She’d then used the iPad to search for the individuals online.

There wasn’t much information on the detectives, who, for obvious reasons, preferred to keep a low profile, but most of the relatives and partners on the list had a presence on Facebook, Twitter and various other social media sites. This enabled Rosa to compile a wealth of useful facts and figures.

She’d then run all the addresses through Google Earth and transferred some of the images of their homes to the phone she’d been given.

At 4am she’d gone through the names again, cross-referencing them against all the other information.

The names of the detectives were typed in a bold, black font and their ranks were included. The boss was a DCS George Drummond. Underneath his name was his wife’s name.

Below him there were several DCIs, and then some DIs, DSs and DCs.

Rosa had circled six names with her pen – Graham Nash, George Drummond, Phil Warren, Laura Jefferson, Dave Prentiss and Gloria Stanford. She’d chosen them for several reasons – they were all based south of the river, they all had husbands, wives or partners who were named, and they all lived in a house and not a flat, which made them more vulnerable.

Before crawling into bed, Rosa had selected her first victim.

She’d also come to the conclusion that with so many victims to choose from this assignment was going to be pretty straightforward.

She started the day as she always did, with two cups of strong black coffee. Then she dressed in a light-grey tank top and jeans.

She’d worked out a plan for the day ahead. First she would go and get something to eat because she’d missed breakfast in the hotel’s small dining room.

Then she’d visit a few stores to buy some things, including clothes, because the few she’d brought with her were for warmer climes.

She would purchase everything using the debit and credit cards that identified her as Maria Rodriquez, which was one of the false names she operated under.