In the cartoon, Casper, as usual, tries to befriend people but finds that everyone is terrified upon encountering a real ghost, even on Halloween. However, at a party, Casper meets a girl called Lou who seems to be prepared to accept him for who he really is.
The cartoon opens with a narrator saying that it is Halloween night, the night when witches, goblins and ghosts come out to frighten people. One exception to this rule is Casper, who, as usual, wants to make friends with people.
Casper notices two costumed boys who are out trick-or-treating. They are impressed by what they think is his ghost costume and invite him to join them. At the first house that Casper goes to, he accidentally passes through the bottom half of a swing door. The homeowner realizes that Casper is a real ghost and flees in terror, pulling up her house from its foundations and taking it with her. The two boys laugh at her for thinking that Casper is a real ghost. When Casper walks through a tree, they realize that the woman was right and run off in terror as well.
Soon afterwards, Casper sees a sign on a barn announcing that a Halloween costume party is being held there and that all are welcome. Casper wants to go in but does not have a costume. Noticing a can of white paint, Casper dips himself in it, making the usually transparent ghost look like someone wearing a ghost costume. At the door, a girl named Lou introduces herself to Casper and invites him to come inside.
Casper joins in the party games and dances. During a dance, a large woman accidentally throws Casper into an apple bobbing tub. The white paint washes off and Casper becomes transparent again. Everybody at the party realizes that he is a real ghost. Most of them scream and run off, terrified. Lou, however, simply laughs. She reveals that she has been wearing a mask and a costume in order to look like a human girl and that she is really a ghost too. Delighted to have finally found a friend, Casper happily skips off with Lou.
- Casper (the 1995 movie)