On a bold plan from The Chief, the leader of a black‑market ring, a batch of jewelry is set to cross from a foreign state into the Soviet Union by hiding it inside the orthopedic cast of a courier. To carry it out, the Chief dispatches a minor henchman, Gennadiy “Gesha” Kozodoyev Andrey Mironov to pose as the courier. Gesha makes his way to Turkey aboard a tourist cruise, while the conspirators back home rely on a simple signal: a code word to identify the real courier.
But misfortune and misidentification throw the plan into chaos. Due to a mix‑up, they mistake the cruise’s other passenger—the ordinary Soviet citizen Semyon Gorbunkov Yuriy Nikulin—for the courier. The criminals wrap the cast around his arm and tuck the contraband jewels inside, while their knowledge about the courier remains only in a whispered code word.
Back in the homeland, Gorbunkov returns and does what any wary traveler might do: he alerts the police to what happened. The arresting plan is spearheaded by a police captain who is secretly undercover as a taxi driver, Stanislav Chekan, who uses Gorbunkov as bait to trap the crooks. Gesha and Lyolik, another henchman played by Anatoliy Papanov Anatoliy Papanov, scheme to lure Gorbunkov into situations where they can quietly, without bloodshed, remove the cast and reclaim the jewels.
One pivotal attempt sees Gesha invite Gorbunkov to a fancy restaurant, hoping to get the man drunk enough for Lyolik to subdue him. Yet both Gesha and Gorbunkov end up in a muddled stupor, and Gorbunkov is carried home by the police after a chaotic scene. His wife, Nadежда Ивановна Горбункова Nina Grebeshkova grows suspicious—finding money and a gun that seems out of place—and wonders if her husband has fallen under foreign intelligence or is having an affair. Gorbunkov insists he is working with the Soviet police on a secret mission, but he cannot reveal any details.
To salvage the operation, the Chief sends Anna Sergeyevna, a female operative who appears on screen as Anna Sergeyevna [Svetlana Svetlichnaya](/actor/svetlana-svetlichnaya, to retrieve the cast. She lures Gorbunkov to her hotel room under the pretense of selling him a gown, and secretly drugs his drink with sleeping pills. The nosy superintendent, who had shadowed Gorbunkov, brings his wife into the room just as Lyolik and the police close in, thwarting the planned capture.
When Gorbunkov awakens, he finds his wife has left with the children, convinced something in his story is a cover for an affair. The police, meanwhile, deduce Gesha’s involvement and pressure Gorbunkov to mention that he plans to travel elsewhere so the cast can be removed there. Gesha reports this to the Chief, who orders Lyolik, disguised as a taxi driver, to retrieve the cast early at a safehouse on the way to Dubrovka. Gorbunkov, thinking Lyolik is also an undercover officer, reveals that he has been in contact with the police all along. Lyolik pretends to cooperate and trips up Gorbunkov, who then attempts to escape as Lyolik and Gesha close in, with the Chief himself lending a hand in the pursuit.
In a dramatic turn, the thieves discover the diamonds are already long gone—the police had removed them from the cast earlier. The criminals resort to kidnapping Gorbunkov and making a hasty escape, only to be tracked down by the authorities with a helicopter. Gorbunkov is eventually reunited with his family, the police explaining the whole affair to his wife. He heads off on vacation with his family, though he carries the physical mark of the ordeal—a broken leg from the kidnapping—as a reminder of the tangled day. Their son, Dmitri Nikolayev, watches his parents’ reunion, underscoring the human cost and the pull of ordinary life back into the frame of extraordinary events.
