Witchaven II takes place after the events of the first game, when the forces of darkness were triumphed over: the witch queen Illwhyrin was destroyed in her lair in the isle of Char and the evil curse was lifted. During the victory party celebrating the destruction of Witchaven, the hero of the game, Grondoval, falls into a slumber. After awaking, he is told by the mysterious female golden dragon named Ikethsti that the great witch Cirae-Argoth, one of the most powerful of Nether-Reaches Order of Witches, has arrived to avenge the death of her sister. An army of demons and Argothonian clansmen has abducted Grondoval's beloved princess Elizabeth and the other people of his homeland Stazhia to exact the titular blood vengeance and now it is only up to Grondoval to try and rescue his countrymen before they will all be gone forever. His new quest is fight his way to find and vanquish Cirae-Argoth, thwarting her plot, and to capture the Horned Skull item which would then contain her evil powers until it could be destroyed.
Source: Wikipedia, "Witchaven II: Blood Vengeance," available under the CC-BY-SA License.