The Addams family face-off against a crafty reality-TV host while also preparing for their extended family to arrive for a major celebration.
Gomez and Morticia Addams move to a derelict asylum in New Jersey, surrounded by a marsh and hidden by a fog at the top of a mountain, to raise a family. Thirteen years later, teaching his son Pugsley the saber tradition of the Addams family while Wednesday is about the world outside the mansion , TV reality host Margaux Needler is busy designing and building the planned community of Ass when the marsh is drained and the Addams home is revealed, Margaux decides to get rid of the Addams Family.—Claudio Carvalho, Rio de Janeiro, Brazil
Gomez (Oscar Isaac) and Morticia Addams (Charlize Theron) are chased away with the rest of the Addams clan during their wedding ceremony by an angry mob that disapproves of their macabre nature. Grandmama (Bette Midler) buys Uncle Fester (Nick Kroll) time to evacuate Gomez, Morticia, and Thing. Gomez and Morticia decide to move from New York to New Jersey, a place "no one would be caught dead in." There, Gomez, Morticia, and Thing find their "perfect" home in an abandoned asylum on a hill. They meet Lurch (Conrad Vernon), an escaped mental patient whom they hit when Thing was distracted driving the car, and immediately recruit him as their butler.
Thirteen years later, the Addams family continue to live their gloomy lives in isolation from the outside world. Gomez prepares his son Pugsley (Finn Wolfhard) for his upcoming Mazurka, a rite of passage that every Addams family member takes. Morticia struggles to keep their daughter, Wednesday (Chloë Grace Moretz), from wanting to experience the world outside of the mansion after a balloon and confetti appear on their property, as the fog surrounding it begins to lift.
Elsewhere, reality TV host Margaux Needler (Allison Janney), who is building a perfect planned community called "Assimilation" so her show will have a successful season finale, discovers the Addams family's household when the fog lifts and becomes determined to rid the town of it when the family refuses to change. Her career and wealth depends on her being able to sell the house she built in the community and they wont sell with the scary Addams house just in the backdrop of the entire town. Wednesday then meets Margaux's neglected daughter Parker (Elsie Fisher) and convinces Morticia to let her attend junior high school. Pugsley struggles with the complicated traditions and pressure of his Mazurka, even with the guidance of Gomez and Uncle Fester. Grandmama arrives at the house for the event.
At school, Wednesday defends Parker and her twin friends Layla and Kayla (Pom Klementieff) from the school bully named Bethany (Chelsea Frei) and befriends them after she resurrects some dead frogs and commands them to attack Bethany. Later on, the two discuss their frustrations and change their dressing habits - Parker becomes more gothic and Wednesday dresses more colorfully - to the shock of both of their mothers. After an argument with Morticia, Wednesday decides to run away in secret and stay with Parker for a while, which Pugsley inadvertently tells Morticia.
Wednesday and Parker discover a secret room under Parker's house revealing that Margaux has planted hidden cameras in every house she designed in town and has been spreading rumors about the Addams family through social media, claiming that they are freaks. Margaux catches the two and locks them in the attic, but Wednesday breaks them out. Margaux rallies an angry mob to attack the mansion just as Cousin Itt (Snoop Dogg) and the entire Addams clan arrive for Pugsley's Mazurka. Even Grandmama's sister Sloom (Jenifer Lewis) will be attending to judge the event.
During the Mazurka, Pugsley fails miserably in front of the whole family, but Gomez reassures him that he is an Addams nonetheless. The mob arrives flinging boulders, severely damaging the mansion and trapping the family inside. Pugsley uses his love of bombs and destruction to defend his family and manages to destroy the mob's Trebuchet. Wednesday and Parker join in and help everyone out of the wreckage safely with help of the living tree Ichabod.
As Margaux tries to take control once more, her treachery is revealed to the people. They see that the Addams are not monsters, but a family, and Wednesday states that everyone is weird in their own unique way. Margaux's agent, Glenn (Tituss Burgess), carries a message from the network stating that her show is now canceled because Parker was live streaming the whole thing with her phone. As Fester comes up with a compromise to Margaux, Assimilation's civilians realize the error of their ways.
After they work together to rebuild the mansion, the Addams family and Assimilation's civilians live in peace. Margaux becomes Fester's business partner, selling homes to the other members of the Addams clan. Pugsley completes his Mazurka.The film ends with an animated recreation of the intro of the 1964 TV show.
