This story took place north of the County, whose peace is guarded by the old witcher John Gregory and his student Thomas Ward. The inhabitants of these lands are defenseless against the creatures of Darkness. And the desperate situation forces the farmer, who received a mortal wound, to enter into a terrible agreement with one of the monsters. In exchange for the right to control the life of his eldest daughter Nessa, the monster, who calls himself the Slither, takes the other two daughters of the farmer to their relatives. This is cruel, but it will save at least two girls from the dangers of the northern lands... Nessa must understand this.