Skipper, Kowalski, Rico and Private join forces with undercover organization The North Wind to stop the villainous Dr. Octavius Brine from destroying the world as we know it.

As the son of a Viking leader on the cusp of manhood, shy Hiccup Horrendous Haddock III faces a rite of passage: he must kill a dragon to prove his warrior mettle. But after downing a feared dragon, he realizes that he no longer wants to destroy it, and instead befriends the beast – which he names Toothless – much to the chagrin of his warrior father.