1866. On a train bound for Portsmouth, an elegant woman shares a compartment with the lecherous Giles Blanchard. It is a lucky encounter for her, as she steps off the train after picking his pocket and in possession of scandalous material for a potential blackmail. It is a less fortuitous meeting for Blanchard, who will never reach his home on the Isle of Wight alive. Detective Inspector Colbeck and Sergeant Leeming are swiftly dispatched to sift through the evidence. With Queen Victoria poised to spend the summer on the island, a speedy resolution to the case is imperative for their superiors. Tracing Blanchard's killer 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?