An obsession with a beautiful serial killer entangles a vampire hunter’s daughter in an immortal sapphic romance in this enthralling gothic fantasy from the #1 New York Times bestselling author of Lucy Undying. Anneke has a complicated relationship with her father, Abraham Van Helsing—doctor, scientist, and madman devoted to studying vampires—up until the night she comes home to find him murdered, with a surreally beautiful woman looming over his body. A woman who leaves no trace behind, other than the dreams and nightmares that plague Anneke every night. Spurred by her desire for vengeance and armed with the latest in forensic and investigatory techniques, Anneke puts together a team of detectives to catch her mysterious serial killer. Because her father isn’t the only inexplicably dead body. There’s a trail of victims across Europe and Anneke is certain they’re all connected. But during the years spent relentlessly hunting the killer, Anneke keeps some crucial evidence to infuriatingly coy letters, addressed only to Anneke, occasionally soaked in blood, and always signed Diavola. Devil. The obsession is mutual, and all the more dangerous for it. The closer Anneke gets to her devil, though, the less sense the world makes. Maybe her father wasn’t a madman, after all. Diavola might be something much worse than a serial killer . . . and much harder to destroy. Because as Anneke unearths more of Diavola’s tragic past, she suspects there’s still a heart somewhere in that undead body. A heart that beats for Anneke alone.