The third volume of the series full of secrets! Snow covers the traces of the crime, but it cannot hide the impurity of the soul. Winter. Several residents of Pełnia are returning home by train. The journey is peaceful until one of the passengers loses their life. The snow-covered town is in a pre-Christmas mood, and Deputy Commissioner Monika Gniewosz and her daughter are settling into their newly purchased home. When someone stumbles upon the body of a woman at the local lake and a case of sexual abuse involving high school students comes to light, the policewoman plunges into the investigation. Soon, another body is found. Do these events have anything to do with the murder on the train? What is going on in the mind of the murderer? The puzzle pieces begin to form a disturbing picture.