Balthazar analyzes a collection of bones discovered in an old abandoned building and finds three bodies dating back to the Middle Ages and one who died a week ago, partially dissolved in acid. The victim's girlfriend, who reported him missing, lives with her parents in a creepy house said to be cursed.

When a woman is found hanged from a bridge, it appears to be straightforward suicide, but Balthazar finds it strange that another victim died the same way days earlier. The fact that both victims had used a blind-dating site before their deaths points to a serial killer targeting women.