The Underwater Bridge

... there is nothing more powerful than the courage of a fearful heart ... 

Fourteen-year-old Gil Lake, haunted by his father's death in a kayaking accident, is at the river with his best-friend Danni and her brother, Percy, when a strange bird drops a hollow stone at Percy's feet. When Gil sees a beautiful green-eyed girl through the stone, Danni throws it into a whirlpool. Percy jumps after it; she leaps to rescue him. Fear holds Gil back a fateful moment before he follows. Drawn ferociously down, he emerges into a winter night. Danni approaches, dressed strangely and carrying a flaming torch. She has been here for months. The whirlpool's "Underwater Bridge" bends time as a prism bends light: they are in ninth-century Britain, in the Norse stronghold of Orkney, after the fall of Camelot ...

Among exiled knights and Viking warlords, Gil finds loyal friends, dangerous enemies, and a cowardly mind-reading pony. He learns horsemanship and swordplay, and, from the Celtic monk, Aidan, the power of the shape-shifting Change-Things. All will be tested as he sets sail on the longship Silver Dragon to challenge the brutal usurper of Camelot, learn the true fate of his father, and find his green-eyed girl.

... Come with him to a land greener and more beautiful and more dangerous than any you have ever known. Come join the Warriors of Tir nan Og ...