Charlie Chan is sought out by Pamela Gray, a desperate young socialite whose brother Paul awaits execution for the murder of a weapons inventor. Pamela is convinced of his innocence.
While visiting the circus with his family, Charlie is recruited by the big top's co-owner to investigate threatening letters that he's received.
Charlie is hired to deliver a pearl necklace to a millionaire at his ranch. When murder intervenes he disguises himself as a Chinese servant and begins sleuthing.
