Aimée Leduc, a Parisian private investigator, has always sworn she would stick to tech investigation—no criminal cases for her. Especially since her father, the late police detective, was killed in the line of duty. But when an old Jewish man approaches Aimée with a top-secret decoding job on behalf of a woman in his synagogue, Aimée unwittingly takes on more than she was expecting. When she goes to drop off her findings at her client's house in the Marais, Paris's historic Jewish quarter, she finds the old woman strangled to death, a swastika carved on her forehead. With the help of her partner, René, Aimée sets out to solve this horrendous crime, but finds herself in an increasingly dangerous web of ancient secrets and buried war crimes.