In the U.S., enemy agent Alexander Vanin of the EEPR goes to a payphone and makes a call. American agents watch him from nearby as Alexander calls his wife, Olga. Alexander gives his wife a series of numbers and tells her to memorize them. The American agents listen in using a parabolic mike and record the numbers. Once Olga hangs up, security chief Valenkoff asks if anything is wrong and Olga assures him that everything is fine.
The agents close in on Alexander, who is forced to flee over a fence and onto a nearby roof. After a chase, Alexander is run to ground. The agent in charge, Kovitch, tells him to turn over the list of his agents active in the U.S.., but Alexander tells him that he’s wasting his time.
Jim picks up his briefing at a flower shop and is informed that Alexander is serving a 20-year sentence for espionage. He hid a list of enemy agents prior to his arrest, and his control, Gregor Mishenko, has been sent to recover it. Alexander hasn’t revealed the list, knowing that his government will abandon him once he tells them where it is. The IMF must find the list.
At the briefing, the team listens to the recording of the numbers: 12-45-72. Jim explains that Alexander used self-hypnosis to make himself forget. Olga has the number and Jim figures that she’s the only one who can unlock her husband’s memory. Willy informs them that the EEPR consulate is preparing a celebration for their country’s 25th anniversary. Paris has the papers and tickets and assures Jim that they’ll be there before noon, contact Olga, and be back by noon the following day. Barney shows them a bomb encased in an epoxy resin. A Geiger tube is inside and it will fire an explosive charge but not the bomb itself. The bomb is set to go off in 53 hours, and they’re using a live detonator because demolition expert Valenkoff won’t be convinced otherwise. The warden at the penitentiary is cooperating with them.
Willy poses as a repairman and rigs the traffic signals outside of the consulate. He then goes down into the sewers. Inside, Mishenko meets with his inside man at the prison, Fitzgerald. Fitzgerald reports that American agents are visiting with Alexander, and Mishenko figures that Alexander will eventually give them the list. The consulate hostess comes in with a list of supplies for the party and Mishenko assures her that it’s okay. Once she leaves, Mishenko tells Fitzgerald to find out what the Americans are up to.
The warden brings Jim and Doug to see Alexander, claiming to be EEPR secret police. They inform the agent that Doug has been given permission to administer a medical examination because Alexander is being repatriated to the EEPR in exchange for a downed American flyer. Jim asks why the Americans are so eager to give him up, accusing him of telling the Americans where the list is. Alexander insists that he hasn’t given up the information. Fitzgerald, a security guard at the prison, takes Alexander to the infirmary.
In Europe, Paris arrives posing as a member of the secret police and asks to see Olga. He says that he has confidential information on her husband and explains that he’s being repatriated. Paris is there to escort her to the U.S. under an assumed name. They want her to help determine whether Alexander has given away the list to the Americans before they bring him back. Once Paris leaves, the clerk calls to verify Paris’ identity. Olga leaves and the clerk gets a response and goes after her. He misses her at the elevator and runs down the stairs, but Dana lures him away by wearing the same clothing. By the time he realizes Dana isn’t Olga, it’s too late to find Olga.
Fitzgerald tells Mishenko about Alexander’s complete examination. He points out that the Americans are doing what they would do if they were repatriating an agent. Mishenko wonders what they’re up to and tells Fitzgerald to kill Alexander.
Willy delivers party supplies to the consulate and Valenkoff takes him in. Once Willy drops off the stack of boxes, Valenkoff has him open the top one and confirms that it contains the alcohol, he and Willy leave. Barney then emerges from the lower boxes, which form a single hidden compartment. He goes down into consulate power room and places the bomb, which has ninety minutes remaining.
Jim and Doug release Alexander, while Fitzgerald watches. Fitzgerald then calls Mishenko and warns that he couldn’t get near Alexander. Valenkoff brings Mishenko a coded message that Olga is missing.
Willy cuts through the sewer wall into the basement, while Barney sets off the silent alarm in the basement. Mishenko sends down Valenkoff and his men, and Barney lets himself be captured.
Paris and Olga arrive in the U.S. and drive to the consulate. A fake radio broadcast announces that Alexander is being exchanged for the flier, and Paris assures Olga that if her husband has maintained his silence then he’ll be returned home.
As they drive away, Jim apologizes to Alexander for his treatment and informs him that their tests have confirmed that he didn’t break. Alexander is unconcerned, noting that he would have done the same, and points out that they’ll arrive at the consulate just in time for the anniversary reception.
Valenkoff informs Mishenko that Barney’s bomb is a potential nuclear weapon and set to go off in an hour. According to his fake ID, Barney is a Cuban agitator. The security man admits that he can’t disconnect or move the bomb, and Mishenko tells Barney to do it under Valenkoff’s supervision while he postpones the reception. If he fails to disarm the bomb, Valenkoff will lock him in and get out of the building.
Alexander points out that Jim and Doug acted differently from the other agents that Mishenko sent him. They were concerned about him, while the others just wanted the information. Doug assures him that Mishenko had many sleepless nights worrying about Alexander, but the agent doesn’t believe it.
Paris tells Olga that her presence is a reward for his heroism, but she realizes that Paris wants her to betray her husband if he talked.
Mishenko is in a limo across the street and has Valenkoff give him updates, and Barney continues to work on defusing the bomb with 48 minutes remaining.
Willy brings in several dozen of the IMF’s repertory players and escorts them through the sewers and into the empty consulate. He then goes back up and signals two truck drivers to get ready.
Dana organizes the repertory players for the fake party that they’ll be hosting. She notices an open heating vent and has one of the players close it, and then make sure that everyone knows what drinks and music that Alexander prefers.
As they approach the consulate, Jim gives a code phrase, alerting the driver to send a signal to Willy. Willy tells the two drivers to move into the position and then sets the traffic lights to stop. The first truck stops between Mishenko’s limo and the consulate entrance. Mishenko is unable to see Jim, Doug, and Alexander get out and enter the consulate. Once they’re inside, Willy lets the traffic signal go green and the truck moves on with Mishenko none the wiser.
Dana plants a bug in Mishenko’s study and then greets Alexander when Jim and Doug bring him in. Dana introduces herself as the new protégé attaché and explains that Mishenko and his wife have been recalled to Washington, and then welcomes him home.
When Paris’ limo approaches the consulate, the driver gives the second signal to Willy. He uses the same trick to block Mishenko’s view of the consulate as Paris escorts Olga inside. While he waits, Mishenko checks in with Valenkoff, who assures him that he’s still there. Mishenko then gets out of the limo and Willy lets the truck go by so that he doesn’t go back to the consulate. Valenkoff admits that they have 29 minutes left and he doesn’t know how much longer it will take to defuse the bomb.
As dancers perform traditional numbers, Alexander asks Dana what was so urgent that Mishenko was recalled. Dana explains that Mishenko is being reprimanded for sending biased reports concerning Alexander’s loyalty. Jim comes over and offers a toast, and Paris escorts Olga in. Husband and wife are reunited, and Paris tells them that they’ll be flown home the next day. The Vanins dance and Alexander realizes that they have brought Olga to determine if he broke. She knows that he doesn’t and tells him that he’s won.
With 24 minutes left, Barney continues to remove the resin epoxy from the trigger device.
As the dancers perform another number, the accordion player inadvertently knocks a chair back, opening the heating vent. In the basement, Valenkoff hears the music from the supposedly abandoned reception hall. Jim notices and closes the vent, but too late. Valenkoff goes upstairs to investigate.
Dana and Paris offer to take the Vanins to the study and Olga says that she has a great deal to tell her husband. As they leave, Valenkoff exits the elevator and stares in surprise at the partygoers. He yells at them to stop, and Doug knocks him out before he can interfere further. Paris goes down to the power room and then impersonates Valenkoff when Mishenko calls for a status report. With two minutes left, Barney works against time to defuse the explosive bolt. He removes the triggering device and Paris-as-Valenkoff reports to Mishenko that it’s safe. Mishenko then has his driver take him to the entrance.
Olga and Alexander discuss his next assignment and hope that they will work together in Europe. They notice that the music outside has stopped and go outside. The reception hall is deserted and Mishenko comes in. He has no idea what is going on or who Dana and Paris are. They realize that the Americans have staged the whole thing and Mishenko derides Alexander as a fool.
As Mishenko leads Alexander and Olga into his study, the IMF listens in via the bug that Dana planted earlier. Alexander tells Mishenko that he couldn’t have told them where the list was because he hypnotized himself. To prove his innocence, Alexander has Olga recite the numbers he gave her before. He then remembers that they are the serial numbers of a bus where he hid the list. Mishenko stops him, realizing that the IMF must have planted bugs in the rooms. He tells his man to track down the bus. Meanwhile, Jim and the others find out where the bus is and Willy drives to the maintenance garage an hour away.
Mishenko, Alexander, and the consulate guard arrive at the garage that night and break in. They get on the bus and go to the seat where Alexander hid the list. He confirms that it’s gone and they prepare to shoot him. However, Jim and Paris come on board and hold them at gunpoint. They show Mishenko the list and Doug leads Alexander off the bus to serve the remainder of his sentence. Mishenko gently asks if they can have Alexander, promising they’ll take good care of him. Jim tells him that he can have Alexander in about 19 years and leaves with the team.