Paul Samson is living in London and picking up some extra work for a private security company when he is almost killed by a thuggish assassin while tailing a mysterious and gifted young employee of a powerful environmental NGO. The murder of legendary spy Robert Harland, the poisoning of billionaire philanthropist Denis Hisami with a neurotoxin in the United States House of Representatives, and a second attempt on Samson's own life send him on the run to Estonia to figure out who is trying to kill him, and why.

Anastasia leaves her comatose husband Denis in the US to join Samson in Estonia and help him get to the bottom of things. Soon it becomes clear that Denis and Harland were running an investigation into a spectral former Stasi agent and her sprawling network of assets across industry and government in the US and the UK when they were attacked. Samson and Anastasia must tap into their research and expose the spymaster before any more people are killed or agencies compromised.

An astonishing and timely thriller examining the penetration of Russian assets into all levels of western life, The Old Enemy is a complex, breathtaking race against time from "one of our most accomplished thriller writers," (Financial Times).