While docked in San Francisco, Captain Sam McVeigh, the tough-talking, hard-drinking skipper of a small cargo ship, sees a beautiful woman standing on the pier and immediately falls in love with her. Later, the woman and Marsden, the man with whom she is traveling, approach McVeigh and ask him for passage on his boat. Unaware that Marsden is not the minister he claims to be, but a fugitive bank robber, and that the woman is not the refined Mrs. Marsden, but Marsden's moll, "Frisco" Kitty, McVeigh agrees to transport the couple. While sailing to Mexico, a drunken McVeigh invites Kitty to his cabin and tries to force himself on her. To his surprise, Kitty thwarts his desires by telling him that his lechery and drunkenness are beneath his station as a captain and that he should clean up his "mind, body and soul." Upon arriving in Mexico, McVeigh, impressed by Kitty's words, stops drinking and tidies his ship, then sends flowers and a grateful farewell note to Kitty. Worried that the authorities will be suspicious of McVeigh's sudden departure, Marsden orders Kitty to flirt with the captain and stall his leaving. Although reluctant to hurt McVeigh, Kitty continues her kindly impersonation of a reverend's wife, while Marsden sabotages McVeigh's engine to assure his delay. That night, Kitty slips away from a drunken Marsden to keep an on-board dinner date with her lovesick captain. After she leaves McVeigh, his crewmen accuse him of the sabotage and threaten to harm Kitty. McVeigh rushes to warn Kitty at her hotel and is confronted by Marsden, who angrily reveals his and Kitty's true identities. Crushed, McVeigh rails against Kitty and knocks out Marsden just as an undercover police detective bursts into the room to arrest Marsden. While Kitty is being held in the hotel, McVeigh sneaks back to her room and accepts her apology and her declaration of love. After Kitty and McVeigh vow to wait for each other, the detective shoots down an escaping Marsden and grants Kitty her release.
