Commissioner Gordon relaxes at home entertaining his young socialite friend Bruce Wayne. Wayne asks if anything exciting has happened lately, and Gordon explains that a fellow called the "Bat-Man" is puzzling him. Gordon receives a call that chemical manufacturer Lambert has been found murdered. They have Lambert's son in custody, whose fingerprints were found on the knife. Gordon invites Bruce Wayne to the Lambert mansion with him, and Bruce Wayne says he has nothing better to do.
When they arrive at the crime scene, young Lambert insists he is innocent. The lad explains that he arrived home early and saw his father lying on the floor. When he entered the library, he saw a figure escaping out the window. He pulled a knife out of his father's back, and his father's last word was "contract." Lambert's son recalls that his father had three associates, Alfred Stryker, Paul Rogers, and Steve Crane. Steve Crane calls Gordon on the phone. Lambert told Crane that he had received a death threat the previous day. Crane has received a similar death threat, and asks for police protection. Bruce Wayne decides to go home, and Gordon rushes over to the Crane residence.
Steven Crane is killed by a gunman who enters through the window. The thug and his partner steal a paper from Crane and climb onto the roof. They are confronted by a figure they recognize as the Bat-Man, standing in the moonlight. The Bat-Man punches the first thug out, then grabs the second one in a headlock and throws him off the second-story roof. He grabs the paper and escapes as Gordon is pulling up. The GCPD try to arrest the Bat-Man, but they are unable to catch him. Gordon learns that Crane has been murdered, and moves on to the next business partner. The Bat-Man smiles when he reads the paper he stole, and drives off in his automobile.
Paul Rogers visits the laboratory of Alfred Stryker, having learned of Lambert's death by news broadcast. Stryker's assistant Jennings clubs Rogers over the head and ties him up. Jennings explains that he will lower a gas chamber over Rogers and kill him the same way he puts animals to sleep. Jennings leaves to activate the gas. The Bat-Man leaps into the room through an open transom, which is some kinda old-timey ceiling window I guess. The Bat-Man grabs a wrench and dives inside the gas chamber before it closes. He plugs the gas jet with a handkerchief, and busts through the glass with his wrench. Jennings returns and tries to pull a gun on the Bat-Man, but the Bat-Man punches him in the face really hard. Alfred Stryker enters and demands to know what happened. When Rogers explains that Jennings tried to kill him, Stryker pulls out a knife to finish the job. The Bat-Man is hiding in the shadows, and he grabs Stryker from behind to stop him.
The Bat-Man explains to Rogers that they were all partners in the Apex Chemical Corporation. Stryker had made secret contracts with all of them to pay them a sum of money each year until he owned the business. He grew tired of waiting and decided to kill them so he wouldn't have to pay. Stryker breaks out of the Bat-Man's grip and pulls a gun on him. The Bat-Man punches Stryker so hard in the face that Stryker breaks through a railing and falls into a tank of acid. The Bat-Man remarks that this is a fitting end for his kind, and leaves via transom. Rogers tries to thank the Bat-Man, but he is already gone.
Later at his house, Commissioner Gordon relates this story to Bruce Wayne. Bruce remarks that this is a lovely fairy tale, and leaves. Gordon thinks to himself that Bruce Wayne is a nice young chap, but he seems to lead a very boring life. Bruce returns home to Wayne Manor, where it's revealed that he is in fact the Bat-Man.
