25 years after their graduation from the Wolfenbüttel Gymnasium in the castle, the graduates of the class of 1989 begin to die one after another. First, it is the farmer Hanno Ackermann, who drives over a landmine from the GDR era with his tractor. While this could certainly be an accident, the next case is crystal clear: the beautiful Ellen Berning-Schäfer is stabbed in her boutique. Hardly have Chief Detective Helmut Jordan and his team discovered the connection between the two deceased when the next member of the class of '89 dies.