The New Year holidays turned into a real detective adventure for four friends - Slavka, Romka, Artem and a girl with the unusual name Leshka! Like real detectives, the guys tracked down criminals: they sat in ambush, changed suspects, put forward various versions and collaborated with the police... And it all started with two seemingly unrelated events. Firstly, Slavka mixed up his things with the luggage of some unfamiliar passenger on the train. And secondly, one day, out of nowhere, in the middle of winter, a huge blue butterfly suddenly appeared in Romka and Leshka’s apartment!