When a sensational killing rocks 1938 London, local newspaper ads offer a hefty sum to the person who can say whodunnit. A man has been shot dead at the top of a Ferris wheel, and his wife --- the only other person in their carriage --- insists on her innocence. But who else could have fired the deadly bullet and escaped unseen? The sheer implausibility of the claim is enough to whip the press into a frenzy. For young and idealistic Edmund Ibbs, the lawyer representing the accused, that frenzy may be his only hope at discovering the truth of the mysterious murder. As he digs into the case, Ibbs unwittingly enters a shadowy web of conspiracy and murder, soon finding himself implicated in not one but two seemingly impossible crimes.

In 1930s London, celebrity psychiatrist Anselm Rees is discovered dead in his locked study. There are no clues, no witnesses and no evidence of the murder weapon. The Scotland Yard detective on the case calls on retired stage magician-turned-part-time sleuth Joseph Spector, who has a knack for explaining the inexplicable, but even he finds that there is more to this mystery than meets the eye. When the investigation dovetails into that of an apparently impossible theft, the detectives consider the possibility that the two transgressions are related. And when a second murder occurs, this time in an impenetrable elevator, they realize that the crime wave will become even more deadly unless they can catch the culprit soon.