JJ embarks on the biggest adventure of his life: Kindergarten. But when, on his first day at school, JJ discovers that his beloved stuffed bear Boba has gone missing, JJ and his friends Cody, CeCe and Nina will begin a quest that will transport them into a magical land ruled by Princess Harmony, who has created a world with one rule: No singing.

An orphaned boy raised by underground creatures called Boxtrolls comes up from the sewers and out of his box to save his family and the town from the evil exterminator, Archibald Snatcher.