Phillip is a wealthy quadriplegic who needs a caretaker to help him with his day-to-day routine in his New York penthouse. He decides to hire Dell, a struggling parolee who's trying to reconnect with his ex and his young son. Despite coming from two different worlds, an unlikely friendship starts to blossom.

As Hiccup fulfills his dream of creating a peaceful dragon utopia, Toothless’ discovery of an untamed, elusive mate draws the Night Fury away. When danger mounts at home and Hiccup’s reign as village chief is tested, both dragon and rider must make impossible decisions to save their kind.