Attempting to rebuild her shattered life on vacation in the South of France, former MI6 operative Kate Henderson receives an unexpected and most unwelcome visit from an old adversary: the UK Prime Minister. He has an extraordinary story to tell --- and he needs her help. A Russian agent has come forward with news that the PM has been the victim of the greatest misinformation play in the history of MI6. It's run out of a special KGB unit that exists for one purpose alone: to process the intelligence from “Agent Dante,” a mole right at the heart of MI6 in London. Against her better judgment, Kate is forced back into the fray in a top-secret, deeply flawed and dangerous investigation. But now she's damaged goods.

Kidnapped in Venice by a Russian defector, Kate Henderson knows she's in trouble. But when he offers her conclusive evidence that the British Prime Minister is a live agent working for Moscow, Kate’s holiday quickly becomes the start of her next mission. The defector has proof of the PM involved in a sordid scandal --- a video supposedly used to blackmail him into Russian service decades prior --- and a financial paper trail that undeniably links him to the Russians, but his motives are anything but clear. Riddled with doubt that the evidence she is presented with may not in fact be as bulletproof as it seems, Kate reopens the investigation into the PM. As she works through the case, Kate runs up against key people at the heart of the British Establishment who refuse to acknowledge the reality in front of them.

To those who don’t really know her, Kate Henderson’s life must seem perfectly ordinary. But she is in fact a senior MI6 officer, who right now is nursing the political equivalent of a nuclear bomb. While heading up the Russia Desk of the Secret Intelligence Service, one of Kate’s undercover operations has revealed some alarming evidence. Evidence that a senior UK politician is a high-level Russian informer. Determined to find out who it is, Kate must risk everything to get to the truth. Until a young woman is brutally murdered as a consequence, which puts Kate and her team under the spotlight. With blood on her hands, her reputation to uphold, her family hanging by a thread and a leadership election looming, Kate is quickly running out of options and out of time.