It's early September in Copenhagen and 36-year-old journalist Heloise Kaldan is in the middle of a nightmare. One of her sources has been caught lying, and she could lose her job over it. Then she receives the first in a series of cryptic and ominous letters from alleged killer Anna Kiel, who is wanted in connection with the fatal stabbing of a young lawyer three years earlier. The letters keep coming, and hint at a connection between Anna and Heloise. As Heloise starts digging deeper, she realises that, to tell Anna's story, she will have to revisit the darkest parts of her own past - confronting someone she swore she'd never see again.