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.

When a man claiming to be long-lost Uncle Fester reappears after 25 years lost, the family plans a celebration to wake the dead. But the kids barely have time to warm up the electric chair before Morticia begins to suspect Fester is fraud when he can't recall any of the details of Fester's life.