A good witch named Winnie, comes to be the live-in housekeeper for Thomas J. Harper (A Widower lawyer), and his three children. This comes at the request of the youngest son, Gene, for someone to help him with bowling.
Winnie's sleazy boss arrives to drag her back to the witch realm, disguising himself as one of T.J.'s clients.
The kids push T.J. into asking Winnie to accompany him to a wedding. However, things go awry when T.J. and Winnie have a difference of opinion about how Winnie should dress.
After Winnie casts a love spell on a girl that Robb has the hots for, Robb learns that he is the only one who can break the spell.
Winnie locks horns with the obnoxious widow of one of Thomas's clients, who has designs on making him her new beau. Meanwhile, Gene records home movies to send to his friends back in New York.
Jessie invites the exclusive clique "The Debs" over for Halloween, but Winnie accidentally turns her invisible and can't reverse the spell.
T.J. buys a car for Winnie and Robb to share, but Winnie ends up hogging it.
While Jessie goes out with an older boy, Gene and Robb trick Winnie into taking them to an X-rated movie.
Winnie imagines herself in the role of "Donna Reed". But trying to be the perfect homemaker backfires when she realizes she is being used for her magic.
T.J. hires Winnie as his secretary, but he becomes miffed when she tries to reunite a couple who are in the midst of a divorce.
Gene worries when T.J. is stuck at a radio station all night due to a massive thunderstorm that has wiped out a bridge, and Winnie's powers.
Winnie gets rid of all of Robb's bad traits, but when she tries to undo her spell, he splits into good Robb and bad Robb.
After a 150-year quest to win Winnie's hand in marriage, a goofy warlock unexpectedly arrives to claim his reward.
Robb is instantly smitten with Winnie's sister Cassandra, but after she briefly whisks him away to Niagra Falls, he becomes so phobic that he refuses to leave the house.