The Sea of Trolls

Borrowing heavily from Norse mythology, this trilogy follows Jack who becomes apprenticed to a Druid bard. When he and his little sister Lucy are captured by Viking Berserkers and taken to the home of King Ivar the Boneless and his half-troll queen, Jack undertakes a vital quest to Jotunheim, home of the trolls. Sequels include The Land of Silver Apples and The Islands of the Blessed.