Jack Flint and the Redthorn Sword

The first installment in the Jack Flint trilogy combines myth, magic, and danger as a boy searches for his long-lost father when he stumbles into a Celtic legend that has come to life
 
Jack Flint is 13. He's never known his mother and has—literally—lost his father. On a stormy Halloween he steps from his humdrum world of school, chores, and getting by, into a maelstrom. Scaling the dark-walled coppice known as Cromwath Blackwood, he and his best friend, Kerry Malone, find a mysterious circle of 13 standing stones—stones that almost seem to be breathing, pulling the boys to a place of myth and mayhem, the legendary world of Temair. Here Celtic myth comes to life as Jack, Kerry, and Corriwen Redthorn, the orphaned daughter of a Temair Chief, face the terrifying cunning of goddess of death Morrigan, along with her servants—the Scree, and the cruel, black-feathered Roaks. As they embark upon their fast paced and furious quest, Jack realizes they are not just saving their own lives, but finding clues that might lead him to his father.