The Trolls are small creatures who live in an almost perpetual state of happiness, singing, dancing and hugging all day. However, they are discovered by the Bergens, large miserable creatures, who can feel happy only after 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 underground tunnels on the day of Trollstice, when Prince Gristle Jr. was going to eat his first Troll. Enraged, Gristle Jr.’s father King Gristle Sr. banishes his Chef who was in charge of the Trollstice preparation. 20 years later, (at the age of 20) Poppy throws a big party to celebrate the Trolls' escape, despite the fears and warnings of the gray troll, Branch, that loud parties will attract the Bergens. A Zen troll named Creek, who is Poppy's boyfriend, arrives and tells Branch to start being happy instead of being grumpy; Branch refuses. At the party, Branch's fears come true, when Chef sees the fireworks and kidnaps Guy Diamond, Biggie with Mr. Dinkles, Fuzzbert, Smidge, Satin with Chenille, D.J. Suki, Cooper, and Creek (which Poppy tried to rescue). Chef then takes the kidnapped Trolls back to Bergen Town, while secretly plotting to overthrow its monarchy in revenge for her banishment. Alone inside the bunker, Branch looks at a bunch of homemade party invitations, indicating that he appreciates Poppy’s offers of friendship and 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 is saved by Branch, who thinks she will not make it if she goes alone. Once inside the Bergen king's castle, Poppy and Branch witness Creek apparently get eaten by Gristle Jr. (who is now king), 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. Poppy discovers that Bridget is secretly in love with King Gristle Jr. and offers to help her get a date with the king while trying to confirm if Creek is alive. While setting Bridget up for the date with an musical number, Branch refuses to sing and triggers an argument with Poppy, revealing that, as a child, his grandmother was captured and got killed while trying to save him, because his singing compromised his location to Chef. Branch's guilt and shame 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 Glitter Sparkles' 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 the king's mantle. Having helped Bridget, the Trolls attempt to rescue Creek from Gristle's room and steal his jewel but discover that it is empty. The Trolls are then captured by Chef and are 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 and they are captured by Chef and the other Bergen cooks. With all the Trolls captured and soon to be eaten, a heartbroken Poppy becomes sad after she had been betrayed by her boyfriend, loses hope as she and all the other Trolls turn gray. Branch sings “True Colors” for the princess to cheer her up, and also confesses his affection for her. Poppy, after regaining her colors, returns Branch's feelings, and they both end up restoring all the trolls' colors including Branch's. Bridget saves the trolls, willing to sacrifice herself. Poppy can't 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 Glitter Sparkles and that it is not necessary to eat Trolls to be happy, and they too, can find happiness within themselves. Chef refuses to accept the peace and tries to kill the Trolls, but is knocked into a serving cart that is sent rolling out of Bergen Town. Chef is set on fire with Creek, who was still in her pouch. 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 Poppy and Branch share a hug. In a mid-credits scene, Chef and Creek's cart stops rolling. Chef prepares to eat Creek herself, but they soon find out they are on top of a monster, who opens his mouth and eats them.
