In the book's beginning, a man named Endithor is attempting to sacrifice a virgin by stabbing her with a knife. Guards, and a city leader named Nalor, break into the room and arrest Endithor before the girl is stabbed. Endithor declares that Nalor betrayed him, and that the whole ritual was planned by Nalor in an effort to supernaturally dispose of a political rival named Kus. Endithor is placed on trial the same day, found guilty, and then is tortured to death in the city square as an entertaining public spectacle. Endithor's daughter Areel watched the execution while also planning her revenge on Nalor, thus she gains the book's title.
That's a lot to unpack, but ultimately Nalor felt that Endithor was becoming a fearsome political rival and just set him up to die. So who is this Kus fellow? That's the really cool part of the book. In flashback scenes, readers discover that Kus was an ancient warrior who fell to his knees on a corpse-strewn battlefield. Approaching death, Kus is “kissed” by a beautiful woman. Kus discovers that the woman was a vampire and that she cursed him with the eternal gift of draining victims of their blood to remain alive and ageless. With the gifts of immortality, Kus also has the ability to shape-shift, control minds, and fly around. Kus sleeps in a coffin in a cold basement because he can't be subjected to sunlight. Both Kus and Nalor form a partnership to protect each other's interests – Kus staying alive and preying on the city while also killing off any of Nalor's political rivals and foes.
Where does Red Sonja fit into all of this? Since she is living in Shadizar at the time of Endithor's execution, she begins to find herself embroiled in the political rivalry. She crosses paths with Areel, learns of Nalor's nefarious ways, and discovers Kus's sorcery and vampiric nature. By teaming up with a local bartender, and a group of mischievous kids, Sonja discovers where Kus is sleeping during the day and then, well, I won't ruin this “fright night” for you.
Needless to say, Endithor's Daughter is an entertaining combination of sword-and-sorcery and Hammer Horror in a not-so-traditional horror presentation. The book's first-half sets up the characters and political strife occurring in the city. The second-half is the quest to find Kus and dispose of Nalor, which takes some time. The book's last 50 pages were exceptional as the story hit its stride and the inevitable “the blade versus the fangs” finally rose to fruition. But, I stress that the reader needs some patience because the novel is heavy on dialogue, less on action. Prepare accordingly, and then enjoy the Hell out of it.