When the famous jeweled garter of the Countess of Salisbury is stolen from the British Museum, The Hawk, a notorious international crook, is suspected of the crime and is trailed by Scotland Yard detectives. The chase leads to the country estate of railroad magnate Brokaw Hamilton, whose daughter Helen is about to elope with the poet Keats Gaunt when The Hawk finds shelter from his pursuers under her window. Helen drops her jewel case, supposedly to Gaunt, but really to the criminal. A few days later, Helen is rescued from drowning by Bruce Calhoun, a mysterious stranger living on a yacht in the harbor, and the two become good friends. Meanwhile, suspicion points to Calhoun as The Hawk and the detectives are now on his trail. Henry Van Derp, a suitor for Helen's hand, is especially vocal in voicing his suspicions of Calhoun. After a series of exciting incidents, including a bank robbery, a yacht explosion and a near train wreck, it develops that Van Derp is The Hawk, and Calhoun a Secret Service agent. The mystery thus resolved, Helen and Calhoun face a happy future together.