This One'll Kill You, Batman! The Joker breaks out of his cell in Arkham Asylum by poisoning the guards with his Joker Venom. Once free, he tries to escape but is confronted by Batman. However, Joker has released several inmates of the Asylum, forcing Batman to fight them instead of concentrating on capturing the main criminal. While Batman is fighting the inmates, Joker drugs him with a special variation of the Joker Venon, which causes Batman to laugh uncontrollably during times of horror, leaving him helpless in battle. Joker is able to escape and Batman is assisted in the fight against the inmates by Two-Face, who acted after the clean side of his coin came up. Batman also learns that it was Two-Face who gave the anonymous tip about Joker's escape, which is why Batman was able to reach Arkham in order to stop the Joker, even though he failed.
A few hours later, Batman is informed that withing the next 72 hours, the drug will make him laugh himself to death unless he can find the one doctor who can save his life before the Joker does. Batman tries to reach one doctor in Gotham City, but the man is murdered by the Joker, forcing Batman to travel to England to find the only other doctor capable of curing him.
Unfortunately, the Joker has reached the doctor first and he forces Batman to struggle against the forced laughter as he tries to save the doctor from being murdered by the Joker, with him as witness. Batman manages to overcome the urge to laugh by thinking of different situations from murder or death and he ultimately manages to stop the Joker and save the doctor. With the Joker captured, the doctor creates an antidote for Batman, curing him of the compulsive laughter.
