Plot
In 1165, [7] the witcher Vesemir saves a child from a leshen in the forests of Kaedwen. Before dying, the creature says something in an archaic elven dialect to Vesemir, leading him to suspect that it was under someone's control. Vesemir is visited by the elf Filavandrel, who thinks the leshen was controlled by Kitsu, one of many elven girls who have gone missing. Meanwhile, the sorceress Tetra Gilcrest, an advisor to the Kaedwen king, argues that witchers should be outlawed and hunted down, but the elderly courtier Lady Zerbst is sympathetic to the witchers and speaks in their favor.
Vesemir reminisces about his youth when he, along with his best friend Illyana, were servants for a noble whose mistress was saved from a mahr by a witcher named Deglan with Vesemir's help. Enticed by promises of fortune and desiring to make a name for himself, Vesemir traveled to Kaer Morhen and underwent the training and mutations to become a witcher.
In the present day, Vesemir and his fellow witcher, Luka, are arrested for killing two Kaedwani knights in a bar fight. Lady Zerbst persuades the king to send Vesemir, accompanied by Tetra to rid the forest of Kitsu. She personally delivers the mission order to Vesemir, who recognizes her as Illyana. Vesemir and Tetra set out and she tells him the story of a young sorceress wrongfully killed by a witcher as part of a con, an act which convinced her that witchers are too powerful and cannot be trusted. They find Kitsu, mutated and now able to cast powerful illusions, and fight her basilisk. They kill the monster, but Kitsu escapes.
Following Kitsu, the pair come across an old and abandoned elven school where they find the bodies of the other missing female elves. They rescue the captured Filavandrel, who explains that Kitsu tried to replicate the experiments that were done on her, and they come to the conclusion that corrupt witchers are responsible, wanting to terrorize the locals into hiring them. Vesemir surmises that the monsters he encountered were probably created in Kaer Morhen and leaves to confront Deglan, who has risen to a high position of leadership. As he departs, Tetra destroys Kitsu's den, finds Kitsu later surveying the destruction, and blames the witchers. Back at court, she reveals the witchers' culpability, and is granted use of the Kaedwani army to lay siege to Kaer Morhen. Illyana sees a captured Luka being put to death and flees to warn Vesemir.
Deglan admits to Vesemir to creating the monsters, including Kitsu, to protect their way of life and are alerted by Illyana of Tetra's assault, which is assisted by Kitsu's monsters. Illyana helps the witcher recruits flee into the mountains. Vesemir confronts Tetra, who has captured the order's mages and is holding them hostage. Kitsu arrives and traps him in an illusion where he never became a witcher, instead having a family with Illyana. However, Vesemir is able to break out of the illusion and engages in a fierce battle with Tetra and her forces. He seemingly kills Tetra and Kitsu, only to realize that Tetra had deceived him with another illusion, killing the mages to destroy the knowledge of creating witchers and mortally wounding Illyana.
Tetra reveals she is the daughter of the sorceress killed by the witcher from her story before the dying Deglan strikes her down. Knowing that the recruits are still alive, he urges Vesemir to guide and watch over them as the new leader. At the behest of Illyana, Vesemir allows Kitsu to flee with her life. Vesemir takes Illyana to a lake, where she always dreamed of living by. The two share a brief moment before she peacefully passes away. He then sets out and catches up to the recruits, including a young Geralt, with the understanding that they are the last of their kind.
