Decktora Raines is on leave from the CIA, trying to escape memories of the agent she lost and the disappearance of her life partner, Alex. But when a Russian defector she once handled unexpectedly reaches out to her, urging her to come to London, her instincts take over. She arrives to find that another Russian defector has been murdered, and the only clues are claw marks and an unidentified white powder.

The bodies pile up, and the Metropolitan Police of London and the public begin to think that a serial killer is on the loose. But Decky and her defector know it's the Russians. And as the claw murders increase, with some of Decky's London contacts falling victim, she must put the bad memories behind her and rely on finely-honed instincts to find the killers and figure out what they have to gain—and how to stop them from killing again.