Preston has been arrested on suspicion of the murder of Mrs Stella Watson, and with the strength of the testimony of Mrs Patricia Stanley, a neighbor of the lady murdered, and a fingerprint taken from the bedroom screen, which resembles his own, it looks certain that he will be convicted. But the fingerprint is not the same! 

A police officer from the case knows the real killer is still on the loose, and is determined to find the real killer, and free the innocent man, Preston, from San Quentin jail!