The Darkest Road (The Fionavar Tapestry, Book 3)

The concluding novel in Kay's trilogy, The Fionavar Tapestry, opens as the fantasy world's magically prolonged winter yields to spring but a spring where showers bring death, emptying entire cities. To combat the arch evil Rakoth Maugrim, the High King of Brennin marches north with his army and allies, anticipating a final confrontation. At the same time, a crucial choice faces young Darien, the son produced by Rakoth's rape of Guinevere. Feeling rejected by the good and the light, Darien sets off on the dark road to his father.