Trolls is a 2016 DreamWorks animated romantic comedy adventure film for kids, based on the lucky troll dolls that were popular in the 80s (you know, the little naked dolls with the giant flourescent hair?).
Trolls are tiny creatures of nearly endless happiness, spending all of their time sing, dancing, and hugging. They also have fast-growing prehensile camoflauging hair which was admittedly pretty neat. Twenty years ago, all of the known trolls were held in captivity by a race of much larger creatures called Bergens, who live in nearly unending unhappiness but who discovered that they can be happy for a short time if they eat a troll. So the Bergens rounded up all the trolls and kept them captive in the center of their town, and once a year on the Trollstice holiday, the Bergens have a feast of trolls and as a result have a day of happiness.
But on that fateful Trollstice twenty years ago King Peppy (Jeffrey Tambor) led the trolls on their escape, burrowing out of their enclosure and out of the Bergen city before they could be eaten. The Bergen chef who was in charge of preparing the Trollstice feast was exiled into the wilderness. Twenty years have passed and the trolls still live free in the woods, unharrassed by their former tormentors.