First movieThe Trolls are small colorful creatures who live in an almost perpetual state of happiness, singing, dancing, hugging, and having fun all day. However, they are discovered by the Bergens, large, ugly miserable creatures, who can only feel happy by eating a Troll. The Bergens imprison the Trolls and eat them every year on a special occasion, called Trollstice. The Trolls, led by their king, King Peppy, with his baby daughter, Princess Poppy, escape through tunnels on the day of Trollstice, when Prince Gristle was going to eat his first Troll. Enraged, Prince Gristles father King Gristle Sr. banishes his Chef, who was in charge of preparing for Trollstice. Chef promises to leave and find the Trolls herself.
20 years later, the now-adult Poppy is retelling the story of how they escaped to a group of young Trolls from a scrapbook. She tells them that she plans to throw a big party to celebrate the Trolls' escape, despite the warnings from the over-cautious and egotistical gray troll, Branch, that loud parties will attract the Bergens. A "Zen" Troll named Creek, who is Poppy's crush, arrives and tells Branch to start being happy instead of being grumpy; Branch refuses. At the party, Branch's warnings come true, when Chef sees the fireworks and kidnaps Poppy's friends, alongside Creek, despite Poppy trying to rescue him and Peppy. Chef then takes the kidnapped Trolls back to Bergen Town, while secretly plotting to overthrow its monarchy as revenge for her exile.
Alone inside the bunker, Branch looks at a bunch of homemade party invitations, indicating that he appreciates Poppy's offers of friendship, has an unrequited love for her, and that internally would like to have fun with the rest of the Trolls. Meanwhile, Poppy goes on a rescue mission alone, as no other Troll is willing to venture to Bergen Town, including Branch. But later on, when Poppy gets into trouble, she's saved by Branch, who thinks she won't make it if she goes alone.
Once inside the Bergen Castle, Poppy and Branch witness Creek getting force-fed to the now-King Gristle Jr. by Chef, but Poppy remains hopeful that Creek survived. Poppy and Branch find the rest of the captured Trolls being guarded by a scullery maid named Bridget (perjoratively called "Idget" by Chef). Poppy discovers that Bridget is secretly in love with King Gristle Jr., and offers to help her get a date with him while trying to confirm if Creek is alive.
While setting Bridget up for the date with a musical number, Branch refuses to sing and triggers an argument with Poppy, revealing that, as a child, his grandmother was captured and got eaten while trying to save him, because his singing compromised his location to Chef. Branch's complete guilt over his grandmother's death caused his color to turn from blue to gray.
After Poppy comforts him with a hug, Branch decides to help Bridget and the Trolls, though he still refuses to sing. Bridget, disguised under the name of "Lady Glittersparkles", gets her date with Gristle Jr. at a roller rink and arcade restaurant, and Gristle Jr. asks her to be his "plus one" at Trollstice. Poppy notices Creek being held captive inside the jewel adorning Gristle's mantle.
Having helped Bridget, the Trolls attempt to rescue Creek from Gristle's room and take his jewel, but discover that it's empty. The Trolls are then captured by Chef, and Poppy gets shocked to discover that Creek sold them out to the Bergens to spare himself from being eaten. Creek lures out every Troll from Troll Village (via Poppy's cowbell), and they're captured by Chef and the other Bergen cooks. With all the Trolls captured, thrown into a pot, and soon to be eaten, a heartbroken Poppy becomes sad and falls into despair after she had been betrayed by her crush, and loses hope as she and all the other Trolls turn gray.
Branch, even though he's gray, tries to sing for Poppy to cheer her up, and also confesses his love for her. Poppy, after regaining her colors and realizing Branch actually cares for her, joins in his song as this makes him happy and he shows his true colors. As the two dance and sing together, the other Trolls get a sense of renewed hope and regain their colors.
Deciding to give back some help, Bridget frees the Trolls from the pot, willing to sacrifice herself. Poppy cannot bring herself to abandon Bridget after her sacrifice that is sure to doom her life, and with Branch and her friends, shows the Bergens that Bridget was Lady Glittersparkles, and that it's not necessary to eat Trolls to be happy, and they too, can find happiness within themselves.
The vengeful Chef refuses to accept the peace and tries to kill the Trolls, but is knocked into the pot and sent rolling out of Bergen Town. Chef is set on fire with Creek, who was still in her fanny pack. Both species celebrate, bringing new life to the town and renewing the life of the Troll Tree. Poppy is then declared queen of the Trolls, and shares a hug with Branch.
In a mid-credits scene, the pot Chef and Creek are on stops rolling. Chef prepares to eat Creek herself, but they soon find out that they're on top of a giant monster, who opens its mouth and eats them both.