A very powerful being is killing Gothamites and the only clue to the killer's identity is graffiti scrawled on the walls of the city's buildings. Batman must solve the puzzle before the body count rises, and face one of the strangest adversaries in his career: the Ogre.
1) 20,000 Volts of Vengeance!: A hooded man and an ape attack a Dr. Belmont. The man makes some remarks about being the sole survivors of an experiment of Dr. Belmont's. He pulls his hood back to reveal a grotesquely disfigured visage. They inject the doctor with a tranquilizer and plug an electrode into his skull. They electrocute their victim, and then call the police. They climb out the window, and the ogre tells his primate companion that he can listen to some Mozart when they get home.
2) The Writing on the Wall: Sgt. Bullock of the GCPD talks to the coroner about their stiff, while Batman is at the scene of the crime and listening in. The coroner tells Bullock that while Dr. Belmont's death may seem gruesome; it was actually quite humane. The victim had been heavily sedated first, and likely never felt a thing. Batman notices some graffiti painted on a wall next to the Dr. Belmont's building directory.
3) Gothic Garret: The ogre and the ape return home to their garret. While the ape puts on a record, the ogre reminisces about their past and paints. It's revealed that he was once a homeless junkie who was coerced into becoming the subject of an experiment to bridge the gap between primates and humans. The ogre paints on his canvas the same graffiti that Batman noticed at Dr. Belmont's office.
4) Intelligence Squared: Batman has done some investigation into Dr. Belmont's past and discovered that he was part of a classified experiment.
5) Man and Ape: A man returns to his home, and is furious to discover that vandals have spray painted his home. He then recognizes the symbol that had been painted and becomes afraid. The ogre catches him and greets him as Dr. Chopra.
6) Murder One Times Two: Alfred enters the Batcave and tells Batman that there's been another murder. Batman goes to the crime scene where the GCPD is on the case. They reveal that it's the same MO as the previous crime, and Batman takes a photo of another graffiti symbol.
7) Ogre's Evolution: Back in their hideout, the ogre reminisces to his companion about their escape from their brutal tormentors. On his canvas, the ogre has added another symbol.
8) Hardback's Hieroglyphics: Commissioner Gordon discusses the graffiti with expert Mackenzie "Hardback" Bock on the roof of the police headquarters. Batman listens in.
9) The Miracle Mistake: Batman is going through Dr. Belmont's records, and uncovers references to something called "Project Mirakle", and "The Murders in the Rue Morgue".
10) Gorillas of Gotham: The ogre picks a lock at the Gotham Zoo, so his companion can socialize with a female ape that he has a crush on. The zoo ape rejects the civilized one's advances, and the ogre reminds him that they are truly alone. They leave to continue their mission of vengeance.
11) Canvas Clues: Gordon calls Bruce Wayne on their scrambled "dark" line. Gordon has remembered where he has seen that graffiti before: it's also been painted at the Gotham Men's Club, and the Knightsbridge Clinic.
12) Gentlemen of Gotham: Bruce Wayne pays a visit to the Gotham's Men Club, and under the guise of applying for membership, he acquires a list of members.
13) Mirakle and Murder: The ogre and the ape have claimed their next victim, but this time Batman arrives before they can make their escape. They battle; and the ape knocks Batman through a wall. The ogre reminds his companion that Batman is innocent and they leave.
14) Erasures and Additions: Batman has Oracle look for information on Project Mirakle. She finds something and he rushes over. Meanwhile, the ogre and the ape have only two people left on their list of vengeance.
15) The Oracle's Advice: Oracle is silently distraught over the information she's uncovered about Project Mirakle. Batman reads through and finds out why. Project Mirakle was an experiment to bridge the gap between humans and apes. The scientists tried to superevolve an ape, and devolve a human. There were only two survivors the experiments, and when they managed to escape; the project was shut down. Oracle begs Batman to stop them. Batman promises he will... if the ogre doesn't do it first.
16) Meeting in the Middle: Batman drives past one of the project doctor's residence, but notices the graffiti and deduces that he's too late. He immediately rushes to the sole remaining doctor.
Meanwhile, the ogre and the ape are in the process of claiming their final victim. This scientist is prepared however, and shoots the ape. The ogre becomes enraged and prepares to jab the electrode into the man's skull, but Batman intervenes. Batman tells the ogre that he cannot allow ANYONE to kill, but he now has the information to make the man pay for what he's done. The ogre decides to prove that he's still human and show mercy. He grabs his companion's body and leaves. The scientist is furious that Batman is just going to let them leave. Batman angrily punches the man and knocks him out. He prepares to bring him to Commissioner Gordon. Elsewhere, Oracle is haunted by the knowledge of the horrible experiments.