Everyone knows about the Cambridge Spies from the Fifties, identified and broken up after passing national secrets to the Soviets for years. But no spy ring was ever unearthed at Oxford.

Because one never existed? Or because it was never found…?

2022: Former spy Simon Sharman is eking out a living in the private sector. When a commission to delve into the financial dealings of a mysterious Russian oligarch comes across his desk, he jumps at the chance. But as Simon investigates, worrying patterns begin to emerge.

His subject made regular trips to Oxford, but for no apparent reason. There are payments from offshore accounts that suddenly just… stop. Has he found what none of his former colleagues believed possible, a Russian spy ring now nestled at the heart of the British Establishment? Or is he just another paranoid ex-spook left out in the cold, obsessed with redemption?