Set 1,300 years after the events of How to Train Your Dragon, dragons are now just a legend to the modern world. When a geological anomaly opens an immense, miles-deep fissure in the Earths surface, scientists from all over the world gather at a new research facility to study the mysterious phenomenon. Soon after, a group of misfit kids uncovers the truth about where dragons have been hiding -- a secret they must keep to protect what they have discovered.