When Rear Admiral Bancroft discovers the plans missing for his new battleship, suspicion falls on Lt. Clifford Bruce, his daughter Madeline's suitor, who was seen climbing out of the Admiral's window. In reality, Bruce, attempting to keep his courtship with Madeline a secret, was retrieving a love letter that he had written the Admiral's daughter. Madeline, suspecting Ito, the house servant, of stealing the plans, takes advantage of the fact that the servant is in love with her and visits his room that night. He shows her the plans which he boasts will bring him a fortune so that the two can elope. Madeline then attempts to gain possession of the papers, and in the ensuing struggle, Ito is stabbed to death. The supposition that he has committed "hari kari" avoids any further investigation, the plans are returned, and the lieutenant wins the consent of the admiral to marry Madeline.

In this propaganda film, athletic silent star George Walsh plays reporter Jack Bartlett, who interviews President Wilson regarding the Fourth Liberty Loan. The story never appears in the paper, however, because its new owner, Otto Crumley, is pro-German. So Jack quits his job and begins canvassing for the Liberty Loans. In the midst of his vigorous campaigning he also halts Crumley's plans to inspire a strike at a munitions plant.

The Love Thief was later reissued as The She Tiger