The movie centers on the conflict between Batman and the Joker, who is poisoning the people of Gotham city. His toxin leaves its victims grinning horribly from ear to ear. The origin of both Batman and the Joker are told during the movie.

The origin of Batman is shown in a flashback, which Bruce has during the movie. The familiar story of how his parents were shot down in front of him on the way home from a movie is hauntingly portrayed. The origin of the Joker is part of the storyline, as Batman accidentally drops Jack Napier into a vat of chemicals while trying to apprehend him. The name Jack Napier was given to the Joker, but his true name is not known in the comics. It is also revealed that it was a young Jack Napier/Joker who killed Bruce's parents.

This was not the case in the comics, but it certainly worked better for a feature length version. The psychotic and physically deformed gangster boss of the movie was certainly more fitting for a live action version compared to the maniac of the comics. A secondary plot exists between Bruce and Vicki Vale. Vicki finds out that Bruce is Batman and they try to work out a relationship. Jack Nicholson is superb in his role as the Joker. Michael Keaton defined the character of Batman and most people consider him the best out of the three actors that have portrayed the role.