Over a millennium after the events of “How to Train Your Dragon,” dragons have faded into myth in the contemporary world. When a massive geological event creates a deep chasm in the Earth’s crust, researchers from across the globe converge at a newly established research center to investigate this enigmatic occurrence. Meanwhile, a band of quirky children, who have accompanied their parents to the site, stumble upon the reality of dragons and their hidden existence. They must guard this revelation closely to safeguard their newfound secret.