Detective Carl Mørck, suffering from PTSD after being held hostage, sends his assistant Rose to the remote island of Bornholm to respond to the repeated requests of his former partner Christian Habersaat. But when Rose finally meets Christian, he takes his own life right in front of her, prompting Rose to delve into the mysterious cold case of a young girl found dead hanging in a tree. This sends Rose on a journey into her own traumatic past and sees Department Q once more engaged in a chilling investigation.