A senior civil servant dies in suspicious circumstances. A sensitive file in his possession and evidence of contact with a human rights lawyer lead the authorities to believe he is a whistle-blower. This needs a police officer used to operating in the murky world between policing and intelligence.

DS Mark (Max) Lomax is a former Special Demonstration Squad officer - a Special Branch unit dedicated to infiltrating political and extremist groups. Following a botched stakeout of a north London gangster, he finds himself on enforced leave and is called back into his old world of half-truths and conflicting agendas.

As he digs into the death of the civil servant, Max is obstructed at every turn, forcing him to turn to the people he once betrayed for help. With political reputations on the line, the case becomes less about uncovering the truth, than burying it for good.