Casper is a kind young ghost who peacefully haunts a mansion in Maine. When specialist James Harvey arrives to communicate with Casper and his fellow spirits, he brings along his teenage daughter, Kat. Casper quickly falls in love with Kat, but their budding relationship is complicated not only by his transparent state, but also by his troublemaking apparition uncles and their mischievous antics.

Siblings Wednesday and Pugsley Addams will stop at nothing to get rid of Pubert, the new baby boy adored by parents Gomez and Morticia. Things go from bad to worse when the new "black widow" nanny, Debbie Jellinsky, launches her plan to add Fester to her collection of dead husbands.