A district attorney prosecutes his own mother for murder.

Jenny Sandoval is pregnant and unmarried when the San Francisco earthquake of 1906 strikes, killing her father, Jim, and her lover, Dan McAllister. Alone, Jenny survives in the Chinese district, where her baby is born, by turning to prostitution. Local attorney Steve Dutton helps Jenny set up a brothel. At a party in his honor, Steve discovers that Ed Harris has cheated him in a crap game and in the ensuing struggle, fatally shoots Harris. Jenny, who is the only witness, calmly hides the gun, but detective Tom Ford charges her with the crime, and Steve arranges to place her son, Dan, with the wealthy Reynolds until the scandal is over. By the time Jenny is able to reclaim Dan, he believes that the foster home is his real home, so she leaves him behind and goes into the bootlegging business with Steve. Years pass and Dan wins the race for district attorney, unaware that Jenny aided him by framing his opponent. Ironically, his first act in office is to break up the vice ring controlled by Steve and Jenny. Steve, fearing arrest, threatens to expose Jenny's past. Determined to protect her child, she kills Steve, is prosecuted by her son, and sentenced to hang. Dan visits Jenny on death row, begging her to reveal her motive. Firm in her devotion, she takes her secret with her to her death.