When District Attorney Harvey Dent collapses after a meal with his fiancée Pamela Isley and friend Bruce Wayne, doctors discover that he has been poisoned. Batman must find the culprit and the antidote before the DA's time runs out.

Mayor Hamilton Hill's miserable son, Jordan, becomes even sadder when his father uses his birthday party as a political gathering, and ends up stowing away in the truck of the party clown hired by Hill for the party, whom he doesn't know is actually the Joker in disguise. It is now up to Batman, whom Mayor Hill distrusts, to rescue the boy before it is too late.