The boss of a black market ring (known only as "The Chief") wants to smuggle a batch of jewelry from a foreign state into the Soviet Union by hiding it inside the orthopedic cast of a courier. The Chief sends a minor henchman named Gennadi…
The boss of a black market ring (known only as "The Chief") wants to smuggle a batch of jewelry from a foreign state into the Soviet Union by hiding it inside the orthopedic cast of a courier. The Chief sends a minor henchman named Gennadiy 'Gesha' Kozodoyev (played by Mironov) to serve as the courier. Kozodoyev travels to Turkey via a tourist cruise ship. The local co-conspirators do not know what the courier looks like; they only know that he is supposed to say a code word to identify himself. Due to a mix-up, they mistake Kozodoyev's fellow passenger from the cruise ship, the "ordinary Soviet citizen" Semyon Gorbunkov (played by Nikulin) for the courier. They place a cast around his arm and put the contraband jewels inside the cast. Upon the cruise ship's return to the Soviet Union, Gorbunkov lets the police know what happened, and the police captain, who is working undercover as a taxi driver, uses Gorbunkov as bait to catch the criminals. Gesha and Lyolik (another of Chief's henchmen, played by Papanov) attempt to lure Gorbunkov into situations where they can quietly, without a wetwork, remove the cast and reclaim the contraband jewels.
On one such occasion, Gesha invites Gorbunkov to a fancy restaurant with the intention of getting Gorbunkov drunk enough for Lyolik to subdue him. However, both Gesha and Gorbunkov become drunk and Gorbunkov is taken home by the police after he and Gesha cause a scene. Gorbunkov's wife begins to suspect either that he has been recruited by foreign intelligence after finding a large amount of money and a gun loaded with blanks in Gorbunkov's possession (previously given to him by the police), or that he is having an affair. Gorbunkov explains that he is working with the Soviet police on a secret mission, but cannot divulge any details. The Chief sends Anna Sergeyevna, a female operative, to help retrieve the cast. Sergeyevna invites Gorbunkov to her hotel room under the pretense of wanting to sell Gorbunkov a gown and spikes his drink with a sleeping pill. As Gorbunkov is about to pass out, his building's nosy superintendent who had followed Gorbunkov brings his wife into the hotel room before either Lyolik or the police can get to him.
Gorbunkov awakens the next morning to find that his wife has assumed that his story was all a cover up for an affair, and has left with the children. The police in the meantime have deduced that Gesha is involved with the smuggling scheme surrounding the cast, and ask Gorbunkov to mention to Gesha that he is planning to travel to another city and will have his cast removed there. Gesha reports this to the Chief, who sends Lyolik disguised as a taxi driver to pick up Gorbunkov. Gorbunkov assumes that Lyolik is also an undercover policeman, and gives away the fact that he has been in contact with the police the entire time. Lyolik plays along and tells Gorbunkov that he has been authorized to remove the cast a day early at a safehouse along the way to Dubrovka. As Lyolik is about to remove the cast, Gorbunkov deduces that Lyolik is actually a criminal and attempts to escape. Lyolik and Gesha chase Gorbunkov and with the help of the Chief himself, they capture Gorbunkov. Upon removing Gorbunkov's cast, they realize that the police had removed the diamonds in the cast a long time ago. The criminals kidnap Gorbunkov and attempt to flee as the police track them down in a helicopter and capture them. Gorbunkov is reunited with his family, with the police having explained the situation to his wife. Gorbunkov goes on vacation with his family, albeit now with a broken leg as a result of the kidnapping.
