The Witcher series, book 5 of 9 completed series

The Witcher is supposed to be a guardian of the innocent, a protector of those in need, a defender against powerful and dangerous monsters that prey on men in dark times. But now, chaos has descended upon the world. The Wizard's Guild has been shattered, and Geralt is seriously injured, helpless until he recovers.

War rages across the land. The future of magic is under threat, and the sorcerers who survive are determined to protect it. It's an impossible situation in which to find one lost girl, Ciri, the heiress to the throne of Cintra, until a rumor places her in the Nilfgaard court, preparing to marry the emperor.

Injured or not, Geralt has a rescue mission on his hands.