The Joker, Vol. 1

Joker and Lex Luthor work together to escape from the police, but as soon as they part ways, Joker decides to follow Luthor to his secret laboratory hideout, where Luthor was using a machine to induce some kind of mind control over Hal Jordan. The Joker bursts in during the experiment and causes a malfunction in the machine which switches the personalities of both master criminals. Joker becomes a genius while Luthor is plagued by an uncontrollable madness.

Joker, using the voice of reason, tries to revert the experiment, but Luthor escapes thanks to his new found mental freedom. With his new genius mental capacity, Joker creates a machine that will revert the process and after a lengthy chase, Joker manages to capture Luthor and their personalities are switched back. Unfortunately, the process leaves the criminals unconscious and allows a young police officer to capture them. Luthor is returned to prison and Joker is taken back to Arkham Asylum, where it is revealed that the Joker has a secret Ha-Hacienda beneath the mental hospital.