Los Angeles cop goes undercover to catch a gang of murderous thieves.

Policeman Tom Collins, in love with Louise Hollister, is compelled to arrest her brother, Roy, who is framed for the murder of another policeman by a gang of robbers. Collins, who believes the boy innocent, disguises himself as a notorious criminal, becomes a member of the gang, and learns that Wolcott, the leader, is the actual killer. He frustrates an attempt to rob banker Pendleton's house, gathers evidence to free Roy, and on the night of Roy's execution, owing to a breakdown in telegraph communications, is forced to race against time through a storm to save the boy. He regains the girl's love and wins a promotion.—AFI