The Peculiar Crimes Unit is a fictitious police department in London charged with solving unusual crimes or those of a politically sensitive nature. When a baby is found murdered in a locked room upstairs during an after-performance party of actors and other theater people, senior detectives Arthur Bryant and John May are called in to investigate.

How was the murder committed, and why do all signs point to an inanimate Punch and Judy doll in the room?

This is just the beginning of a macabre series of murders involving Punch and Judy dolls, Madame Tussaud-type dummies, and other Grand Guignol touches. This is the ninth novel in the Bryant and May mystery series and one of the eeriest. Bryant, the unconventional "brains" of the unit, is a shambling, forgetful, and poorly dressed character who seems like a combination of Sherlock Holmes and Columbo. May is younger, neater, and more of a standard police professional. Together, they make a strong combination.

In addition to the intricate John Dickson Carr-type plot, what carries the story along is the entertaining verbal interplay between Bryant, May, and the other members of the team as they chase clues, interview suspects, and try to figure out the offbeat methods of their unusual leader, all of which leads finally to the grand finale where, in true, old-time detective tradition, Bryant gathers all of the suspects into a room and unmasks the killer.