Three men on duty spend Christmas Eve at the police station in the 13th arrondissement of Paris in Croulebarbe. They talk about everything that is connected with such an extraordinary service, and all firmly believe that in the silent and holy night there will be peace from crime. He believes that the blaring of the police alarm that evening can only be caused by a lonely drunk who decides to share the oppressive loneliness of Christmas night with the police officers on duty. At that moment, none of them have any idea that the seven crosses marking the places on the map of Paris from which the police alarms sounded that night will be the key to uncovering a serious crime.
The story of Zdena (M. Fišerová) and Maria (V. Galatíková) in the two-part television play by Markéta Zinnerová is about finding the complex relationship between daughter-in-law and mother-in-law.
A detective story about Srdicko (heart) -- a double meaning in this case: it is a gold antique heart-shaped piece of jewelry that is the subject of the search, but also the heart failure of Mrs. Mari.