A terrible crime occurred at the walls of the St. John the Baptist Monastery! One of the nuns was killed, and early in the morning a peasant boy found her body in the snow. The motive for the crime is known to few: on behalf of Mother Superior, Sister Evdokia was going to take to the city a large uncut emerald that had disappeared after her death. Who knew the true value of the treasure, which the nuns themselves until recently considered a simple stone? How could the killer walk across a snowy field without leaving a trace? Dasha Bestuzheva and her friend Petya Makarov recently unraveled a complex case, and therefore the bishop personally asked them to take part in the investigation. But will young people really be able to find the criminal and the stone, even if the police have reached a dead end?