Childhood friends Johanna and Kristine once shared secrets in their playhouse, Villa Lupin, but drifted apart. Years later, Johanna returns home to care for her ailing sister, only to find Kristine brutally murdered, the case unsolved, and their playhouse demolished. Johanna possesses knowledge the police overlooked, yet she hides her suspicions, instead channeling her theories into a private novel that she knows can never be published. She also dedicates herself to documenting the destruction of old gardens and historic villas by developers, preserving memories and nature.

However, everything changes when Kristine's son, Lukas, is also found dead, an apparent accident at the family's country estate. Fearing for Lukas's sister, Elise, and feeling a deep sense of responsibility, Johanna realizes it's time to stop merely playing with a manuscript and actively unravel the past. Kristine's talent for making enemies provides many leads: the mysterious women at Lukas's funeral, the enigmatic Anna with her black dog, and the secrets hidden at the desolate country house.