The Hour of 13

In 1890 London, Nicholas Revel, who travels easily among society's upper crust; MacStreet, who works for an insurance company largely doing appraisals; and Ernie Perker, a hansom cab driver secretly work together to commit thefts, usually of expensive jewels. Needing money to pay off debts, Nicky, the mastermind of the three, plans to steal the Calgurie Emerald right off the neck of its owner, wealthy Mrs. Chumley Orr, at a party she is hosting, the party when she is sure to wear it. Nicky's plan is despite or because Scotland Yard Superintendent Sir Herbert Frensham will be at the party, Nicky's rationale being that Frensham will be too preoccupied with the rash of yet unsolved murders of police constables by someone calling himself "The Terror". The ultimate plan is for Ernie, who will "find" the emerald in the back of his cab, to return it for the several thousand pound insurance money. Creating a diversion at the party, Nicky is able successfully to carry out the theft. Because of the resulting circumstances of evidence of the theft being found at the scene of the latest murder, Nicky senses an opportunity to direct suspicion away from himself and toward whoever The Terror is. In the process of that secondary plan, Nicky befriends the Superintendent's daughter, Jane Frensham, as her fiance, Sir Christopher Lenhurst, a military man, is necessarily detained for a few weeks and as she, intrigued by Nicky's musings, wants to play amateur detective with him to nab The Terror. That friendship has unintended consequences as the Superintendent's assistant, Connor, begins to believe that Good Samaritan Nicky isn't all he appears to be--and could indeed be the thief/murderer.