Mamie Smith is rescued from an orphanage by Mrs. Caldwell, the mother of a small child whom Mamie calls Zander.  Mrs. Caldwell dies, and Mamie takes Zander west in search of the boy's missing father.

In Arizona she meets Dan Murchison, a liquor smuggler who pretends to be Caldwell in order to avoid the sheriff.  Mamie falls in love with Dan but learns of his illegal activities and threatens to inform on him.  Dan locks her up and sends Zander to his friend Juan for safekeeping.  Mamie escapes and is captured by Black Bart's gang, who tie her to a tree.  She frees herself and goes to Juan's men, arriving in time to round up the gang members.

Dan tells Mamie that he is not Caldwell, and she and Dan are married.