May, 1941. One of the senior choristers at St Paul's, Edwin Roberts, is found beaten to death in the crypt of the cathedral and Detective Chief Inspector Coburg and Sergeant Lampson are called in to investigate. The dead man was far from popular. That, coupled with a small army of staff at work at the famous landmark, including those on the Night Watch striving to protect the cathedral from the worst of the Blitz, means that there is no shortage of suspects. The case is complicated further by links to the top-secret war work being carried out at Bletchley Park and by the black market in rare books and valuable art which casts its shadow over St Paul's. When the killer strikes again, St Paul's is in danger of becoming known as a place of death rather than worship, and Coburg and Lampson are under pressure to get to the bottom of a fiendishly complex investigation.