On her first night as a dockside taxi dancer, Mary Foster loses her job when she tries to fend off the advances of drunken sailor Groder. As Mary walks in the streets, she is followed by a policeman who intends to arrest her for prostitution. Mary panics and hides in Captain Grant's freighter, on which Groder is first mate. After they set sail, she is discovered by second mate Tommy, and gives in to his advances. She spends the night in his cabin, and Tommy falls in love with her as he gets to know her. In the morning, Groder discovers Mary's presence and sneaks into Tommy's cabin. Tommy comes to Mary's rescue as Groder assaults her, and knocks Groder against the porthole, where he collapses. Unknown to Tommy and Mary, Groder has been stabbed by shipmate Mackie, whom he bilked out of some money from an illegal business they conducted. Captain Grant charges Tommy with murder and arranges for his and Mary's arrest on their arrival in San Francisco. Once there, however, the ship's steward surprises everyone by revealing he is Inspector Redding of Customs. While investigating Groder and Mackie's drug smuggling, he witnessed Groder's murder. Tommy and Mary are released and decide to pursue their romance ashore and marry.