Jun Shibata (Miki Nakatani), an elite detective candidate and Tokyo University graduate, is assigned to the Metropolitan Police Department's Second Investigation Division, a unit responsible for handling unsolved criminal cases.
There, she meets Tōru Mayama (Atsuro Watabe), an experienced but seemingly unmotivated detective who has become accustomed to working on cases nobody else can solve.
On her very first day, Jun becomes interested in a strange complaint from a man who claims to have received a telephone call from someone who was murdered a year earlier.
As Jun investigates, she begins uncovering suspicious details surrounding the murder and challenges the assumptions of her new colleagues.