In San Francisco in the Gold Rush days of the 1850s, a district attorney is prosecuting a long gang leader for murder. However, a powerful political boss is protecting the killer, and he gets off. Outraged citizens form a lynch mob, but before they can accomplish their task another murder is committed, and the culprit appears to be the brother of the District Attorney`s fiancé. The D.A. believes the young man was framed for the murder to take the heat off of the gangster`s acquittal, and sets out to find the real killer and who is behind him.