Five years after uniting the dragons and Vikings of Berk, Hiccup and Toothless soar beyond their homeland, charting the vast unknown. During one of their adventures, the pair discover a secret cave that houses hundreds of wild dragons -- and a mysterious dragon rider with a startling connection to Hiccup. And as the ruthless dragon conqueror Drago Bludvist rises to seize control of both dragons and people alike, Hiccup must step into his role as a true leader and, alongside his friends and Toothless, protect Berk from a devastating war.