'Her name is Maisie Jenks and that's her father with her. They live up in St. John's Wood way, and she knows who the murderer is ...'William Tarrant is on trial for the murder of a police constable. Before he can give evidence in his own defence, however, he is shot in Court 1 of the Old Bailey. In his debut case, Detective-Inspector Simon Manton has to solve the puzzle of a missing juror, a nervous warder, and a girl, Maisie, who screams just before the deadly shot is fired ...