Marjorie falls under suspicion of murder when a child in her care consumes poisoned chocolates. Abetted by a policeman who has fallen in love with her, her uncle Marcus attempts to film a reenactment of the crime in the hopes of deducing how the murderer poisoned the chocolates. But when Marcus himself is murdered on film in front of several witnesses, the celebrated Dr. Gideon Fell must unravel the most ingenious plot. Carr, the master of misdirection, has tremendous fun incorporating stage magic, the psychology of perception, and clever clues.