Watch The Witcher: Nightmare of the Wolf (2021) online

Vesemir visits Kaer Morhen where he reluctantly oversees the training of new children recruits. Later he, and another fellow witcher, Luka, are arrested for killing two knights who had insulted them in a tavern. Tetra implores the king to execute the imprisoned witchers, but Lady Zerbst persuades the king to instead send Vesemir along with Tetra to rid the forest of Kitsu. She personally delivers the mission order to Vesemir and reveals herself as a much older Illyana, contrasting with the young-looking Vesemir, who ages slowly due to his alterations. Vesemir and Tetra travel the forest in search of Kitsu, and she tells him the story of a young sorceress wrongfully killed by a witcher as part of a con, and that she is convinced that all witchers are "corrupted". They find the girl, who can now cast powerful illusions due to a mutation, and fight her basilisk. They kill the monster, but Kitsu flees further into the forest.

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 was done on her, and they come to the conclusion that witchers were responsible, creating new monsters to palliate their declining numbers. He then leaves the premises with a surviving hybrid young elven girl, swearing that if she ever harms anyone, he'll call for Vesemir's sword. Vesemir surmises that the monsters he encountered were probably created in Kaer Morhen and leaves to confront his mentor, master witcher Deglan. As he departs, Tetra destroys Kitsu's den and goes to find her. Back to the court, she convinces the king of the witchers responsibility in the recent monsters attacks and is given authorisation to lay siege to Kaer Morhen, while Lady Zerbst's plea fails to stop Luka's execution.

Deglan admits to Vesemir to creating the monsters, to sustain their work and their way of life, and they both fight. Before it can escalate further, they are alerted by Illyana of Tetra's assault. Tetra, who had lied to Kitsu about the destruction of her den and the disappearance of the hybrid girl, uses her control over the monsters to aid the townsfolk of Ard Carraigh into wiping out the witchers. Illyana helps the recruits flee Kaer Morhen while the witchers defend their home.

Although they put up a good fight, the witchers are massacred due to the sheer number of enemies. Deglan, seeing the folly in his actions, tries to hold off the horde while Vesemir confronts Tetra, who has captured the mages and is holding them hostage in the basement. Kitsu arrives and plunges Vesemir into an illusion where he married Illyana and had a family. However, Vesemir is able to break out of the illusion and engages in a fierce battle with Tetra and her forces. He kills Tetra and stabs Kitsu, only for it to be revealed as an other illusion, and he had killed a mage and stabbed Illyana instead.

Tetra attacks Vesemir from behind, and she reveals she is the daughter of the sorceress killed by the swindling witcher (implied to be Vesemir), explaining her hatred for their kind. Before she can deal the final blow, Tetra is killed by a dying Deglan who asks Vesemir to find the children and make them into "better men" before succumbing to his wounds. At the behest of Illyana, Vesemir allows Kitsu to flee, and he carries a dying Illyana from the burning castle.

Vesemir takes Illyana to a lake, where she always dreamed of living by. The two share a brief moment before she peacefully passes away, leaving a grieving Vesemir behind. He then sets out and catches up to the children. He throws them their witcher medallions and asks them to choose to become witchers or walk away. One of them states that everyone will hate them, to which Vesemir smirks and replies, "There will always be more monsters, Geralt." The boys contemplate Vesemir's words before picking up their medallions.