One of the major villains in the series is Emhyr (Bart Edwards), the tyrannical emperor of the Nilfgaardian, and Ciri's father.
In the season three finale, Ciri appears to be captured and returned to the emperor. However, when they reunite in a ceremony in the Nilgaardian banquet hall, viewers realize that "Ciri" is actually Teryn (Frances Pooley), a girl who has been hypnotized and believes she is Ciri.
Emhyr doesn't realize it is not her daughter and welcomes her to his kingdom, allowing Vilgefortz, his right-hand sorcerer, to continue with his plan.