Baptism of Fire by Andrzej Sapkowski

A deadly coup within the Wizard's Guild leaves the Witcher, Geralt of Rivia, gravely injured, and his ward Ciri missing in the third novel of Andrzej Sapkowski's groundbreaking epic fantasy series that inspired the hit Netflix show and the blockbuster video games. 
 
The Wizards Guild has been shattered by a coup, an uprising that has left Geralt seriously injured. 

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 that dark times have fallen upon the world, Geralt is helpless until he has recovered.

While war rages across the lands, the future of magic is under threat and those sorcerers who survive are determined to protect it. It's an impossible situation in which to find one girl—Ciri, the heiress to the throne of Cintra—until a rumor places her in the Niflgaard court, preparing to marry the Emperor.

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

Witcher collections
The Last Wish
Sword of Destiny

Witcher novels
Blood of Elves
The Time of Contempt
Baptism of Fire 
The Tower of Swallows
Lady of the Lake
Season of Storms

Hussite Trilogy
The Tower of Fools
Warriors of God