Paris has been a city overshadowed by secrets for ages. Under the lights of the lamp posts and charming cobblestone streets, a lot of stories hide in the shadows. Claire Moreau, a detective, understands this well.
She receives a forgotten letter that leads her to a beautiful old mansion. The letter tells of a murder that remains unsolved in Paris for many years. Claire does not go through this journey by herself. Julien, a reliable officer, accompanies her in the search for abandoned buildings, secret passageways, and dusty documentations.
As Claire is trying to put all pieces together, the mansion starts revealing her secrets to her.