Howard Lamson is District Attorney and his interests are directed toward the arrest and conviction of a gang of crooks dealing in lottery tickets. Moving in respectable society is Wallace Thorpe about whom nothing definite is known. The District Attorney’s sister, Shirley Lamson, plunges into settlement work to forget a great disappointment and unconsciously becomes a leading figure in the arrest of the law breakers and comes dangerously close to becoming a victim of the ring leader, Wallace Thorpe. One of the purchasers of lottery tickets under the stress of the third degree, breathes the name of Thorpe, and playfully at first, but in earnest at last, the District Attorney suspects Wallace Thorpe because of the similarity of the name. Thorpe chafes under the joke giving rise to the first real suspicion against him. Harmon, detective for the District Attorney, traces several parties who have purchased lottery tickets, and in the hope of convicting Thorpe on their evidence, arrests Thorpe and the case comes to trial. Additional mystery is lent the situation by the newspaper report of the fact that the man who first gave the name of Thorpe to the police was later found stabbed to death with a card, the Ace of Spades, pinned to his coat. At the trial the mystical symbol plays a most important part, the witnesses on whom the District Attorney relied being intimidated by a unique use of the ace of spades. As a result, contrary to expectations, staunch denials are made by the witnesses and the District Attorney lost his case against Thorpe. About this time the District Attorney’s sister opens a club room for men in the slums, and after several unsuccessful efforts to launch it, finally attracts the attention of the lottery gang, and they use it for their own meeting purposes. The incidents move very rapidly from this point. Harmon, detective for the District Attorney, trails the gang to the club room and arrests them. Thorpe escapes, and jumping into a taxi, stops at the corner where Shirley, the District Attorney’s sister, is waiting for a car. He kidnaps her and places her aboard a Blue Star steamer, disguised as a helpless invalid in a wheel chair. Visiting the District Attorney, Thorpe tells him he has his sister in his power and demands his release as a condition of her freedom. In a gun duel the District Attorney gets the upper hand and succeeds in making Thorpe his prisoner and freeing his sister, Shirley.