A disembodied head solves Victorian murders while hunting for her own body. The mystery isn't whether she'll find it, it's what she'll have to become once she does. Aya Rindo is immortal, sharp, and completely unhinged about her predicament, which means every case is filtered through someone who has already lost everything and has nothing left to lose but answers.

In the 19th century, vampires, werewolves, golems and other paranormal beings share the world with humans. Aya Rindo is an immortal beauty who exists only as a head. She travels through Europe with Tsugaru Shinuchi, a half-human, half-demon fighter known as the Demon Killer, and her faithful maid Shizuku Hasei. Working as supernatural detectives, they take on cases involving the paranormal while hunting for the man who took Aya's body and Tsugaru's humanity. One case sees them hired by the vampire noble Jean Duchet Godard in France after his wife is murdered in her own home and the human authorities refuse to look into it properly.