Greetings, my dark and twisted friend. Let me tell you a tale that will make your bones rattle with delight. Many moons ago, the Addams family ancestors found a little spot in what is now Central Park, long before it was civilized. They thrived for generations, and a massive mansion was eventually erected over their ancestral graves. Of course, they had to plant a great Spanish oak, known as the Addams Family Tree, to protect their final resting place from sunlight and tourists.

As the story unfolds, the last dead leaf of autumn falls from the Family Tree, and all is well in the eerie, morbid world of Gomez, Morticia, Fester, Grandma, Wednesday, Pugsley, and Lurch. They gather in the family graveyard, as they do every year, to celebrate the duality of life and death and to connect with their past for a better future. They seem to be at peace, not just with each other and their unchanging Addams-ness, but with their deceased ancestors, who rise from their graves on this night every year to join in the festivities of continuity. But, oh, how quickly things change when Fester blocks the ancestors’ return to their graves. The unchanging Addams family values are about to be put to the test.

Fester seeks their aid in setting things right, just in case a new family secret goes horribly wrong. What is the secret, you ask? Well, Wednesday Addams, the bundle of malevolence that we all adore, has grown up and fallen in love. But wait, there’s a catch – the young man, Lucas Beineke, is from Ohio, and his parents are coming over to dinner to meet the family. Two different worlds are about to collide, my friend. Will love conquer all, or will they all go home feeling glum and dejected? Gomez and Morticia are understandably wary. Wednesday is their baby, even if she’s now eighteen. Their worries escalate into terror when they overhear her singing a cheerful tune and falling head over heels in love. Like any concerned parents, they wonder where they went wrong.

But Wednesday begs her parents not to cancel the dinner, and she encourages the entire family to act as “normal” as possible when Lucas and his parents arrive. She loves her family just the way they are, but they clearly fall outside the realm of what the Middle-American Beinekes are used to, and Wednesday’s afraid that, if his parents don’t approve of her, they’ll take Lucas back to Ohio, and she’ll never see him again. But fear not, my friend, for the Addams family promises to do their best to oblige. Meanwhile, Pugsley, having witnessed Wednesday and Lucas making out, is worried that he’s lost his best friend to her disgustingly sunny disposition. So, he plots to break up the happy couple by stealing a volatile potion from Grandma’s private stash – Acrimonium – that brings out the dark side in anyone who drinks it.

After what’s likely to be an abnormal dinner, Wednesday hushes the table for Lucas’s surprise announcement. But before that happens, it’s time for the traditional Addams family game, “Full Disclosure,” during which everyone takes a sip from a sacred chalice and reveals something they’ve never told anyone. Gomez tries in vain to calm Morticia. Fester announces that he’s fallen in love with the moon. And when it’s Wednesday’s turn, Pugsley seizes his chance! He secretly pours the Acrimonium potion into the chalice and passes it to his sister. But things go awry when Alice intercepts the chalice and downs the potion, unleashing a whole new, very dark and uninhibited version of herself. The powerful poison prompts Alice to reveal the long-buried problems in her marriage, humiliating Mal, who’s fed up with all the weird and creepy events of the evening and decides to leave, taking Alice and Lucas with him. But chaos erupts when Wednesday blurts out the news that she and Lucas are getting married. The two families clash, and Fester urges the Family Ancestors to work some magic, whipping up a sudden, terrible storm and trapping the Beinekes with the Addams family for the night.