The story starts during a Sword-fighting-at-Sea lesson during a storm. Hiccup attempts to fight with Dogsbreath the Duhbrian, but ends up losing the fight and is almost killed. But the fight is cut off as the wave tips the boat over and is holed by an object. Hiccup realizes it is a coffin and he and Fishlegs ride on it back to the Isle of Berk, where the others, surprisingly have survived too. It is clearly the property of Grimbeard the Ghastly, the greatest pirate who ever lived and Hiccup's own great-great grandfather, according to the words inscribed on it. Gobber and the boys bring it back to the Great Hall for it to be opened. When it is opened it, they find out that it contains a living man(at first mistaking it to be Grimbeard's corpse), soon to become Hiccup's worst enemy, a man named Alvin the Treacherous. He does not reveal his true name, telling them his name is Alvin the Poor-but-Honest-Farmer, and tells them of how he found the coffin when he was farming, and when he opened it, it snapped his hand off. He shows the Vikings that he has a hook to replace it. He then tells them that he found a riddle that tells where to find the treasure of Grimbeard the Ghastly and a map that shows the island where the treasure is. The islands treasure turns out to be a decoy, but nobody knows except Hiccup. It turns out that Alvin is actually an Outcast, Alvin takes his crew to capture the Hairy Hooligans. A fight on the Hooligan’s Ship cause Hiccup, Fishlegs, Alvin to drown