Charlie Chan at the Circus (1936)

Charlie receives 14 free passes to the circus for him and his entire family but soon realizes that strings are attached--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 his father's enthusiastic assistant, is distracted by the show's beautiful contortionist.