
Alvin tries to kill Hiccup to keep him from taking any treasure. Toothless finds a door that opens into a cavern full of gold and jewels - Grimbeard's real treasure. The ship sinks to the bottom of the sea, and they all escape into an underwater cavern filled with air. Everyone escapes except for Hiccup, Fishlegs, Alvin the Treacherous, and Toothless. As they fight, their ship is boarded by the Outcast Tribe and Alvin is revealed to be the Chief of the Outcasts. On the way back to Hooligan Village, the Hooligans fight over the treasure and who the successor to Stoick should be. Hiccup is nearly killed by a Skullion, but is saved by his father, Stoick the Vast. However, Grimbeard the Ghastly booby-trapped the chest with a smell that will wake up all of the resident Skullions - huge ear-less, eyeless dragons with an unusually keen sense of smell. Snotface Snotlout and his dragon Fireworm triumphantly sniff out a chest full of treasure, as well as Grimbeard's infamous sword, Stormblade. The Hairy Hooligans go to the island mentioned in the riddle which is determined to be the dangerous Isle of the Skullions. Alvin shares a riddle that tells where to find the treasure of Grimbeard the Ghastly, and convinces them to search for it. When the Hairy Hooligans decide to open the coffin, they find it contains a live person who calls himself Alvin the Poor but Honest Farmer. Hiccup and Fishlegs find a coffin floating out at sea after a disastrous Swordfighting-at-Sea lesson. When Hiccup finds a coffin at sea, he opens it to discover a riddle that will lead to the treasure of Grimbeard the Ghastly, the world's greatest pirate and Hiccup's ancestor.Setting out on a treasure hunt, Hiccup and his friends must master the art of swordfighting! How else will they escape an island of homicidal dragons, defeat a boatload of Viking pirates, and survive a dirty double cross?
