Charlie Holmes lives alone in Nantes in an old house that resembles an English manor house, with her grandfather George Holmes, the son of the famous British detective Sherlock Holmes, an absent father who left a bitter memory for him. Charlie suffers from mood disorders and is on medication, but one day, an accident awakens her conscience. She secretly stops taking the drugs that her grandfather makes her take every day and feels unsuspected talents developing within her, which enable her to go from a menial post in the police complaints office to the status of an extraordinary investigator and to follow in her great-grandfather's footsteps with the help of Samy Vatel, a forensic trainee who becomes, in a way, her Doctor Watson.
