Mlle. De Loir, a pretty actress, has her jewels stolen out of her dressing room in some unaccountable manner. She cannot be consoled until her maid suggests they send for Tom, Dick and Harry, three famous detectives who have never gone astray on any case. The three arrive with numerous disguises and make-ups and get to work at once digging out clues and asking questions. Little Tom finds the footprints of a rat in the talcum powder on the actress's dressing table. He needs no further clue. I will disguise myself as a cat and catch the thief. Donning the paraphernalia of a cat he watches at a hole in the floor until he sees the guilty rat going through. He follows it to its home and there sure enough are the missing jewels. Gathering them up he seeks his confreres and together they wait upon Mlle. De Loir and present her with her gems, restored through the sagacity and intelligence of those past masters of the detective's art, Tom, Dick and Harry.
—Moving Picture World synopsis