Dorothy Evans, a chemistry teacher at her aunt's girls school, hopes to satisfy her yearning for adventure when she vacations with her aunt, who desires to wear men's clothes, at a secluded island in the Chesapeake Bay. On the boat, they witness officers shooting an escaping prisoner diving overboard. On the island, a gang of crooks vacate the cottage belonging to Dorothy and her aunt, but leave behind a bottle of nitroglycerin. Dorothy recognizes it, and after dumping the contents into the bay, she fills it with her aunt's heart medicine. After the prisoner is taken in by the crooks and volunteers to get the "soup," Dorothy surprises him with a revolver and binds him to a chair. They fall in love, and when the gang tries to rescue him, he fights them. Dorothy's threat to drop the nitro bottle leads to the gang's capture. After the officers identify their "prisoner" as a famous detective Harold Vance, Dorothy and Harold plan to marry.