Warden Gracie had faith in mankind, and he believed that kindly encouragement would achieve better results in dealing with convicts than harshness and brutality. In this he differed radically from Samuel Green, whom he superseded as warden of the state penitentiary at San Pedro. The major's lovely daughter shared his views. Her feeling for Daniel Craig, known as "Three Sevens" in the prison where he was serving twenty years for a murder of which he was not guilty, was not based upon theory, but upon sentiment and admiration.
In escaping from the prison, Craig unintentionally brought about the release of five desperate and hardened criminals, as well as a number of others, willingly, whom he felt had reasonable claims to freedom and another chance. To undo the injury done society by letting the five outlaws escape, and to retain and strengthen Joan Gracie's feelings for him, Craig resolves to devote himself to the recapture of the five. In carrying out this purpose he experiences a number of exciting adventures and often is close to death.