Hiccup is now into adulthood, young but now the leader among the Dragon-rescuing Vikings of their island fortress village of Berk.  Though the Vikings have lived in Berk for generations, Hiccup soon sees that they’ve outgrown their small island, especially with the overcrowding of the Dragons there as they rescue more of them, eyeing the mythical sanctuary on the edge of the world to guide these magical beasts.  Meanwhile, love may be in the air, with Hiccup perhaps on the verge of marriage with Astrid, though she seems reticent, and Toothless perhaps finding a mate with a female Dragon very much like him, dubbed a “Light Fury” due to its alabaster color, in contrast to Toothless’ obsidian appearance. Unfortunately, it's all a trap set by Grimmel, the notorious hunter of Night Fury dragons, who aims to snuff them all out at any cost.