Russian detectives unwind the ball of the most intricate and cruel crimes. They are consummate professionals, the best cops in town. Even on the most dangerous missions, this quartet never loses their sense of humor. It is it that helps them find the most incredible ways out of any situation. They uphold the law and emerge victorious.

Evgeny Korolev arrives in Moscow by train and meets his future friend there - a red-haired first-year student Vladimir Vladimirovich Kvakusha. In addition to this guy with a funny last name, Zhenya recognizes Sasha, the head of the first-year students, who falls in love with him without memory. However, Zhenya himself falls in love with a third-year student, Veronika, whose boyfriend, Anton Sedykh, has great ties with the deputy dean Pavel Ilyich Gusev. As for Gusev, he hates Dean Vesnovsky and wants to take his place with all his might. Gusev's behavior affected not only teachers and students, but also Evgenia: he was once expelled from the student dormitory. However, he remembers that he has a friend Kvakusha, who is always ready to help him: the whole problem is that Kvakusha is a master at creating problems, and it is very difficult to solve them later.

Misha is a professional conman who framed his boss and "dumped" him for a lot of money. To avoid deadly consequences, he escapes to his hometown. On the very first day, Misha stands up for his long-time love Natasha, quarrels with the main criminal authority named Don and accidentally gets a job with the police. Now he catches criminals himself, simultaneously escaping from the killer and trying to establish a personal life.

From a simple misunderstanding, a kind, funny story has grown about charming village people, about ridiculous situations in which they periodically find themselves.

A poker player and expert in psychology investigates cases in an unorthodox way.

1941. Georgy Volkov, Captain of the State Security Service, is delivering to the Soviet Union a consignment of emeralds under a trade agreement between the USSR and Germany.