Danish journalist Heloise Kaldan is in the middle of a nightmare when she receives the first in a series of cryptic letters from a woman named Anna Kiel. Wanted in connection with the fatal stabbing of a young lawyer three years earlier, Anna hasn't been seen since. The police think she's fled the country, until the reporter who originally wrote about the case is found murdered. Has Anna Kiel struck again, or is there more than one killer at large? And why does every clue point directly to Heloise Kaldan? 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.