In the shadows of betrayal and vengeance, the Russian bear awakens, targeting the architects of operations and their defecting fugitives in a deadly game of cat and mouse. The Russians, driven by a burning desire for revenge after their failures, set their sights on those they believe have wronged them inside and outside Russia. The UK's security services and the architects of the Enez operation find themselves in the crosshairs. The Russians dispatch teams to execute their deadly plans.

Amidst the turmoil, Hugh and Michelle continue to hide, far away from the yacht and house that were once their home. They must continue to navigate a treacherous landscape of deception and violence. The security service bosses still want Hugh and Michelle, as well as the money under their control. MI6 persuades Uliana Doubek to join. There, she will help run the finance system.

The Harper sisters, too, face mortal threats, forcing them to confront the consequences of their past choices. Tom and Effi narrowly avoided becoming victims of Russian revenge and are now a critical part of the response.

MI5, MI6, and the police unite to devise a desperate plan. Kathrine returns from suspension to lead the response. Will it be enough to stop the Russians and prevent more catastrophic losses?