"You got Slayer problems? You know what I find works real good with Slayers? Killing them." — Spike
It's 1940, and Europe is ravaged by World War II — an ideal environment for demon paramours Spike and Drusilla. The anniversary of Dru's resurrection as a vamp impends, and Spike wants to celebrate. What better gift than Freyja's Strand — a powerful necklace rumored to allow its wearer to shape-shift at will? Spike learns of a demon named Skrymir, who claims to possess the bauble and is willing to trade.
Spike's task is to infiltrate the Watcher's Council headquarters and get his hands on the list of young women in training to take over as Slayer should they be called. In exchange for Freya's Strand, Spike must kill the reining Slayer, a brazen young woman named Sophie, as well as the Slayers-in-Waiting. And if he succeeds, it could mean the end of the Chosen One — all of the Chosen Ones — forever…
The story takes place between March and September 1940, during the World War II. In 1943, Spike would be eventually kidnapped into a German U-boat ("Why We Fight").
Drusilla celebrates eighty years as a vampire, turned in 1860 ("Darla").
A flashback with Vikings takes place in the year 837.
Spike is described with blond white hair; by 1943, he would have his hair dyed black ("Why We Fight").
Mr. Travers and Miss Fontaine talk about ideally having a hundred Slayers, not knowing that sixty years later thousands of Potential Slayers would be activated ("Chosen").
Spike kills Alessandra Cavallaro using railroad spikes, his trademark weapon at the time ("School Hard").
Kakistos is revealed to be the same vampire in Missouri that eventually made Faith hassle an alligator, as she describes in "Faith, Hope & Trick".
The Council recognizes Spike as the vampire who has killed a Slayer in 1900, as seen in "Fool for Love".
Drusilla questions Spike if they'll ever return to America; the vampire would attend Woodstock in 1969 (as mentioned in "School Hard"), fight a Slayer in New York City in 1977 ("Lies My Parents Told Me"), and both arrive in Sunnydale in 1997 ("School Hard").
Spike is bothered by the suggestion of returning to Prague for he and Drusilla have almost being killed by a mob; in 1997, Drusilla is eventually captured and tortured there (The Problem with Vampires).
Sophie dies killed by Spike, which contradicts the fact that he killed only two Slayers: Xin Rong and Nikki Wood ("Fool for Love").
This is the first Buffy the Vampire Slayer novel in which title character Buffy Summers does not appear, and the only in which she is not even mentioned.
About writing a Buffy the Vampire Slayer horror story, Golden has said: "I do think it was much easier for me to write a horror story in that universe without Buffy. That doesn't mean you can't do it with Buffy, but it's not easy to balance the snark with the dread and revulsion and fear that you want. I do think that Nancy [Holder] and I pulled that off — to a certain degree — with 'Immortal', but that's because we set out to do that very thing. […] Unfortunately the bookstores did not have any interest in putting a Buffy novel anywhere but the YA section, so for both that and the 'Spike & Dru' novel, I tried to say as often and as publicly as possible that those books were not appropriate for young readers. They were never intended for the eleven- and twelve-year-olds who were on the young end of the readership of the earlier Buffy novels."
The vampire Gorm refers to Gorm the Old, the first historically recognized ruler of Denmark.
(Narration) - Spike had seen enough in his life to believe anything, but he knew he did not believe in gods. There had been a time when monsters stalked the long nights, and then there had come a time of heroes, men and women brave enough to face the things in the dark. Not gods, just humans. The monsters, though, he certainly believed in those.
(Narration) - Humans — the living, breathing kind — sometimes seemed to exist only as ghosts to [Drusilla]. And the things that only she could see, the surreal whispers of other worlds and other powers, those were rich with life and power. There were times when Spike envied her the color and vibrancy of the world in which only she could travel. This was not one of those times.
Yanna - "Evil is the vampire's nature. I do not claim to understand them. Yes there is something about this Spike that draws me, confounds me, even awes me, in a way no dark power or demon ever has. I cannot define what that magnetism is, except to say this: He rejoices in evil. I have seen him once, in the flesh. And I have seen him so many times in my head. Evil is ecstasy for him. There is so much joy for him in death and suffering that it undermines everything I have ever believed in."
Eleanor - "I don't mean just afraid of the vampires who are huntin' us. I mean… more than that. Just… are you afraid to be the Slayer? 'Cause I am. Here I am, bein' trained to replace y'all when you die. If I'm next to be Chosen, that is. But you're so nice to me, protectin' me, even though just bein' around me's gotta be a constant reminder of how short Slayers' lives usually are."