My Lady Incog. (1916)

Financial troubles force Nell Carroll, a thoroughbred, to seek employment in a detective agency which has just taken up the trail of a very baffling jewelry robbery in an exclusive summer colony. In order to work from the inside, she is sent to the place as the Baroness Du Vassey. Suspicion promptly fastens upon Teddy De Veaux, the son of the woman who first invites Nell to her home. Every evidence points to him until the leader of the crooks, suspecting the real identity of the "baroness." decides to present himself as the Baron Du Vassey, her husband. The arrival of the "baron" causes consternation in the heart of Nell, who does not know whether she is facing an impostor or has chanced upon the name of a real nobleman. Trusting to chance to give her some hint as to the truth, she decides to face the man and attempt to outwit him. But more than wits are necessary to defeat the crook, with whom the butler is allied. It comes to a question of a steady hand and quick trigger finger when the thieves are caught red-handed and spring upon the innocent young Teddy.