1866. On a train bound for Portsmouth, an elegant woman shares a first-class compartment with a gentleman in a celebratory mood. Giles Blanchard reveals his lecherous side as the journey gets underway, but he will never reach his home on the Isle of Wight alive. This chance encounter is to prove fortuitous for the woman and her partner-in-crime. They find themselves not only the richer for picking the dead man's pocket, they also now possess the material for an extremely lucrative blackmail.

Detective Inspector Colbeck and Sergeant Leeming are swiftly dispatched to sift through the evidence. They are all too aware that with Her Majesty Queen Victoria spending the summer on the island, a speedy resolution to the case is a priority for their superiors. Tracing the pair who lured Blanchard to his death is an endeavour freighted with difficulties, but will the fact that their inquiries lead them to the door of a royal residence be one complication too many?