Dirk Thamsen intended to spend a joyful evening at his class reunion in Niebüll with former classmates and take a break from police work. However, he is pulled back into it sooner than expected: the former German teacher, Rita Hansen, is found strangled in the women's restroom. Thamsen is shaken but immediately initiates an investigation. By the next morning, there is another victim. To solve the case, Thamsen, with the help of his friend Haie, must delve deep into the past.