Throughout the first season, Thulin and Hess try to hunt down the serial killer known as The Chestnut Man before he can claim another victim. The detectives eventually connect similar details of several murder victims: they had body parts cut off, they were single mothers, and they each had a history of the government being involved in their children’s care.
While Thulin and Hess try to track down the Chestnut Man, they also try to find out what happened to a politician’s young teenage daughter named Kristine Hartung (Celine Mortensen). Her mother, Rosa (Iben Dorner), is the Minister of Social Affairs, and Kristine was previously reported dead despite her body never being found. The ambiguity of Kristine’s situation is prevalent throughout the show, and we don’t find out her status until the season finale.
The detectives originally think Kristine’s disappearance may be linked to a nurse named Benedikte Skans (Simone Lykke), whose child was taken away as a result of legislation that Rosa passed. While Skans and her boyfriend do have Rosa’s other child Gustav (Louis Næss-Schmidt) in their custody at one point, they don’t hurt him, and they are revealed to be innocent of anything involving Kristine.
Eventually, the true killer — to be revealed shortly — leads Thulin and Hess to the place where he’s been keeping Kristine. She’s understandably shaken, but not physically harmed, and she’s reunited with her mother.