"The Case of the Chemical Syndicate" by Bob Kane (& Bill Finger).
Article by Bryan Stroud
"The "Bat-Man," a mysterious and adventurous figure fighting for righteousness and apprehending the wrong doer, in his lone battle against the evil forces of society… His identity remains unknown."
The story begins in the home of Commissioner Gordon, who's entertaining his "young socialite friend, Bruce Wayne." Bruce is sucking on a pipe while Gordon works on a cigar and the Commissioner mentions that this fellow called the "Bat-Man" puzzles him. It is then that the telephone rings and Gordon learns that the Chemical King, Lambert, has been stabbed to death and his son's fingerprints are on the knife. The Commissioner invites Bruce along and they speed to the Lambert mansion. After visiting the crime scene, Gordon goes to another room in the mansion where a clean-cut but semi-hysterical Lambert proclaims his innocence. He explains that as he was walking by the library he heard a groan. Upon entering, he discovered his father on the floor and noticed the safe was open. He also got the impression that someone had just leaped through the window. Pulling the knife from his father's body, he heard the man's last words, which were "…contract…contract…" That explains the fingerprints on the murder weapon. The Commissioner asks if Lambert's father had any enemies or people with interests in his business activities. The youth recalls his three former business partners, Steven Crane, Paul Rogers and Alfred Stryker. Just then the phone rings and its Steve Crane, trying to reach the elder Lambert. Gordon takes the call and learns that Lambert had called Crane the day before and told him of an anonymous threat on his life. Now Crane has received one, too. James Gordon tells him to sit tight until the police can get to his house. Bruce Wayne takes the opportunity to depart and allow the Commissioner to do his work.
We then segue to the library of Steven Crane, just in time to see an armed figure take his life and then a paper from his wall safe before slipping out the window. Pulling himself to the rooftop, he meets his accomplice and confirms that he has the paper. It is only then that they discover they are not alone on the moonlit roof. The menacing figure of the Bat-Man is there and soon he leaps into action, decking the first hood and sending the second flying with a judo toss. His gloved (not gauntleted) hand grasps the paper and leaves the roof before the police, who have recently arrived on the scene, can question him.
Crane's butler informs Commissioner Gordon that Mr. Crane has been murdered. Gordon says they'll go to Rogers' home next.
The story fades back to the dark figure of the Bat-Man, who has read the paper. Smiling grimly, he speeds away in his car (a less than subtle red car that looks nothing like a Batmobile) to an unknown destination.
We now join Rogers, who has learned of Lambert's death by news broadcast. He's decided to visit Alfred Stryker, but no sooner has the man at the door let him in than he, Jennings, lays him out with a blow from a blackjack. Jennings then carries Rogers to the basement laboratory and ties him up while cackling to himself that one more is out of the way and soon he'll control everything. When Rogers comes to, Jennings points out a glass enclosure above his head. It's a gas chamber that he uses to kill guinea pigs for experiments. Once he lowers it, the gas will kill Rogers. Jennings starts the mechanism that lowers the chamber and then exits to turn on the gas. It is then that the Bat-Man leaps through an open transom, scoops up a wrench from a table and leaps forward before the gas chamber covers Rogers. The mysterious caped figure then uses a plain old handkerchief to plug up the gas jets before swinging the monkey wrench and shattering the gas chamber. When Jennings returns, he pulls a gun, but the Bat-Man is too fast for him, administering a flying tackle followed by a left that leaves him in dreamland.
Moments later, Alfred Stryker arrives and asks Rogers what has happened. His former colleague informs him that his assistant, Jennings, has tried to kill him. Stryker quickly pulls a knife and says that he'll finish the job and then drop Rogers' body into the acid tank below. Once again, it's the Bat-Man to the rescue as he springs from the shadows and disarms Alfred Stryker. When Rogers asks why he tried to kill him, the Bat-Man, while holding Stryker tightly by the lapels, speaks for the first time: "This rat was behind the murders! You see, I learned that you, Lambert, Crane and Stryker were once partners in the Apex Chemical Corporation…Stryker, who wished to be sole owner, but having no ready cash, made secret contracts with you, to pay a certain sum of money each year until he owned the business. He figured by killing you and stealing the contracts, he wouldn't have to pay this money."
Following this revelation, Stryker breaks free of the grasp of the Bat-Man and pulls a pistol from his jacket. A terrific left sends Stryker tumbling over the edge of the platform and into the acid tank. The Bat-Man merely comments, "A fitting ending for his kind." He then slips away.
We now switch scenes back to the home of Commissioner James Gordon where Bruce Wayne is again in attendance. Gordon is relating the story to Bruce, who seems to be fairly bored by it all. The last two panels, however, let the readers in on a little secret: Bruce Wayne returns home to his room…a little later his door slowly opens…and reveals its occupant…if the Commissioner could see his young friend now…he'd be amazed to learn that he is the "Bat-Man!"