A model who poses for 'naughty' postcard photos but moonlights as a prostitute blackmailing her clients is found strangled in the park.

Inspector Murdoch investigates shooting of vaudeville comedian Bert Grady who is found dead on the street, shot three times in the chest. Grady had just finished his performance at the Bradley theatre, with Constables Crabtree and Higgins in the audience. The shooting looks like - or was made to look like - a robbery. He was not well-liked by others in the show, including a young juggler by the name of W.C. Fields and Ed Ward, Grady's one time comedic partner who is now far less popular on his own. The police find Grady's hotel room ransacked and suspect someone may have been out to steal his jokes. Would-be comedians Crabtree and Higgins join the show undercover and quickly identify Grady's mistress, Eleanor Moffat, wife of the show's manager, Lewis Moffat who became aware of their affair a week ago. A buried body gives them the clue to solving the crime.

Murdoch has to investigate after a murder is transmitted over James Pendrick's new invention.