During a set of winter holidays, all the dragons of Berk unexpectedly depart, leaving everyone distraught. The only exception seems to be of Toothless, who cannot fly by himself. Out of compassion, Hiccup creates him a new prosthesis allowing him independent flight, and thus allows his escape. Three days later, Meatlug, a Gronkle dragon whom Fishlegs had kept chained, escapes, inadvertently taking Hiccup. Meatlug travels to a sulfur-hot springs island where the other dragons have been hatching their eggs. Astrid and the gang also discover Dragon eggs in Meatlug’s nest, which they scatter around Berk in hopes of lifting the villagers’ spirits. This plan backfires because dragon eggs hatch with an explosion, devastating Berk.
While looking for Toothless, Hiccup meets Stormfly (Astrid’s Deadly Nadder), Hookfang (Snotlout’s Monstrous Nightmare) and their babies. Wanting to get a ride home, Hiccup inadvertently triggers their return migration. Despite the devastation, Berk citizens are filled with joy to see their dragons back.
During the ensuing celebration, Toothless returns, having spent the entire time away looking for Hiccup’s lost helmet. The next day, Toothless destroys his new tail and compels Hiccup to put the old saddle on him and be his rider again. Hiccup closes the short saying that he had given Toothless a great gift (freedom), but Toothless gave him a better one (friendship and maybe more…).