Batman has traveled to the future to find a vaccine for a disease. He’s allied himself with Kamandi, the Last Boy on Earth, and his friend, the dog-humanoid Dr. Canus. Having acquired the vaccine, Kamandi and Canus are trying to get Batman back to the time fissure through a ruined city devastated by the Great Disaster. Ratmen chase them through the ruins and Batman drops the first wave of attackers into the street. He tells Kamandi and Dr. Canus to go ahead while he holds off the rest and then slips into the sewers. A ratman in sewer gear follows him as he gets to the raft where Kamandi and Canus are paddling toward the time fissure atop the Statue of Liberty. Kamandi knocks the ratman out with paddle but the other ratmen are in hot pursuit. They get to the Statue of Liberty and Batman tells them to look in its left nostril before leaving via the time fissure. Kamandi and Canus climb the statue and find a time capsule, that Batman left for them in their past when he went back to his present. Kamandi takes out the energy blaster inside and drives back the ratmen.
In London, the spirit of Batman arises from a grave with his name on it. He remembers how he was battling the Gentleman Ghost, who had acquired a quill pen and was seeking two other artifacts with which to raise an army of the dead. The Ghost is able to stay one step ahead of the Caped Crusader despite Batman’s armory of Nth metal weapons. Finally the Gentleman Ghost knocks Batman out, takes him to a cemetery, and buries him in a booby-trapped coffin.
Using his Tibetan meditation techniques, Batman astrally projects himself out of the coffin and finds a ghost hovering nearby. Batman explains that he only has two hours of air left and his air runs out at midnight. The ghost demonstrates his own ability, as he possesses a passerby and takes control of his body. However, Batman doesn’t want to endanger a civilian by having the ghost use its host body to open his coffin. They take off into the night.
The Gentleman Ghost visits a fake medium and reveals her tricks. However, he takes the very real magical key that she is using as a decoration: the second artifact.
Batman sees a glowing light in the sky and the ghost explains it’s a portal to the Other Side. Batman sees his dead parents, Thomas and Martha, waiting for him. The ghost warns that once he goes to the Other Side, there’s no coming back. Batman considers the portal and then draws back, realizing that it’s not his time and he has unfinished business. His parents disappear and the ghost says that Batman is a fool for not going into the portal. Batman says he still has crime to fight and needs a hero who can recover his body.
Green Arrow and his teen sidekick, Speedy, are chasing a thief across the rooftops of London. They capture him and the unseen Batman spirit finds them. Once the ghost explains only dead people can see them, he shoves Batman into Speedy’s body. Batman tries to explain but gives it up. When he leaves, Speedy wonders what happens and Green Arrow demonstrates his own Batman impersonation. Disgusted, Batman gets back into Speedy and knocks Green Arrow to the ground. Green Arrow is convinced and Batman explains what happened and what they need to do. Green Arrow and the restored Speedy head for Brigands’ Hill Cemetery where Batman’s coffin is, while the ghost complains about how miserable the Gentleman Ghost can make his “life.” A fed up Batman tells him to get over his self-pity and find the reason he has his powers. Batman departs and the ghost follows him to apologize. The ghost explains that he used to be circus acrobat Boston Brand, known as “Deadman,” and was assassinated by a man with a hook on a hand. Batman knows that he’s Boston Brand, who performed at Haley’s Circus. Batman is working to solve the case, but tells him to help or give up.
As Green Arrow and Speedy start digging, Batman finds the Gentleman Ghost at the Museum of Torture obtaining the third artifact: the hangman’s noose that killed him. The two of them fight and Gentleman Ghost gets the upper hand. However, Deadman makes his entrance and the Gentleman Ghost flees on a skeletal ghost steed. They follow him beneath the cemetery where there are catacombs filled with the bones of the convicts. The Ghost uses the three relics to perform a ritual and summon forth the spirits of the dead criminals. They start to pull Batman into the earth and Deadman tries to help, but Batman tells him to get the Nth metal weapons in his utility belt. Deadman leaves and the spirits enter their skeletal remains as the Ghost sends them out to burn London to the ground.
With only a few minute left, Green Arrow and Speedy bypass the coffin booby traps and free Batman. Deadman enters the Caped Crusader’s body and uses an explosive capsule to blow a hole in the ground to the catacombs below. The Gentleman Ghost bursts up and summons forth his army to attack the archers. Below, Deadman arrives in Batman’s body and uses the Nth metal weaponry to free Batman’s spirit. Batman demands his body back and they go to the surface where Deadman possesses Speedy and joins the battle. Green Arrow takes out the Ghost’s steed with an Nth metal arrowhead and Batman hits him with Nth metal brass knuckles. The Ghost loses the artifacts and the spirits turn against him, pulling him down. Batman tries to save him but the convict ghosts leave with the Gentleman Ghost.
Batman promises Deadman he’ll find his killer. Deadman rises up into the air and finally sees the white light he’s been waiting for.
Three months later, Batman has been captured by the Triad. Their leader prepares to kill Batman… and Deadman takes over his body. He explains that he figures he’s got a new goal in “life” and plans to have some fun in the process. Together the heroes go after the Triad.