Charlie receives fourteen free passes to the circus for him and his entire family but soon realizes that there are strings attached as the big top's co-owner asks his guest to investigate threatening letters that he's received. Before the famous detective can, the man is murdered. Charlie soon finds out that the co-owner was not a particularly pleasant or well-liked individual, and among the many suspects are his partner, a snake charmer and the menagerie's gorilla. Son Lee, usually an enthusiastic assistant for his father, is distracted by the show's beautiful contortionist.