MacGyver has slipped into East Germany to get a valuable microfilm from his contact, Fritz. Fritz is hunting in the woods and after they confirm each other's identities, he gives MacGyver the microfilm hidden in a shotgun cell. Soviet soldiers are on to MacGyver and surround him, and he tries to talk his way out of the situation. When that doesn't work, he tosses one of Fritz's birds to the soldiers' dogs, distracting them long enough for both men to make a run for it. He gets to a nearby road but a police car and a motorcycle cut him off. However, the police car breaks and the motorcycle drive skids out of control. MacGyver's friend Craig Bannister is driving the police car.
MacGyver gets in and Craig drives them down a mountain toward the border. The soldiers open fire and one shot severs a brake line. The car goes out of control and MacGyver has Craig pop the hood. He then climbs out onto the engine and rigs a line to transfer the power steering fluid into the brake cylinder. They crash through the border gate and Craig gets control of the car just in time.
MacGyver returns to the states and goes to DXS headquarters. On the way in he chats with Fritz, a security guard, and delivers some correspondence from his relatives in East Germany. MacGyver then drops in to visit Craig, who is kissing his new wife Ingrid. Craig introduces Ingrid and MacGyver offers him their bet wishes. MacGyver finally gets to the office of the new executive director: his friend Pete Thornton. Pete informs him that they've lost four agents in the last two months because of a mole within the organization. He wants MacGyver to help him but MacGyver begs off, saying he's in the middle of moving.
Later, MacGyver is packing when Pete comes by and asks again. DXS has gained access to a Russian defector, a former GRU member, who can identity the key Soviet agents in the States. Pete figures that the mole will attempt to kill her, and MacGyver is the only one he knows he can trust. MacGyver refuses but they're interrupted when the defector, Viktoria Tomanova, comes in against Pete's wishes. MacGyver argue with Pete over using Viktoria as bait, but she insists that she wants to help. She accuses MacGyver of cowardice and leaves, but Pete stays long enough to invite MacGyver to a science symposium where both DXS and Russian Intelligence will have a high profile. MacGyver agrees to help out his friend.
MacGyver arrives at the symposium in a tuxedo, and Craig Bannister and Ingrid come over to talk to him. Pete comes in with Viktoria on his arm and thanks MacGyver for showing up. As they look at an ultrasonic beam exhibit, Viktoria spots the GRU head of operations, Anton Lem. Viktoria refuses to leave even though Lem knows who she is and why she's there.
Reverent Mather calls the symposium to order and gives a speech on brotherhood and international awareness. As he talks, Lem pushes a button on a small transmitter device. Mather starts to ramble and clutches at his forehead. Lem sends a signal a second time and Mather reaches into the podium and pulls out a gun. He opens fire on Viktoria, who dives for cover. MacGyver grabs the ultrasonic beam projector and focuses it on Mather, shattering his glasses and causing him to collapse. Craig and MacGyver check Mather, but they're unaware that Lem is using his transmitter to send a different signal. Mather has a heart attack and they're unable to revive him.
Mather's body is taken to the morgue where the pathologist discovers a mass of fibrous matter blocking the heart. MacGyver convinces him to provide a sample so MacGyver can analyze it on his own. Outside he talks with Pete and Craig, and they're all convinced it was no coincidence that Mather specifically opened fire on Viktoria. MacGyver figures that the mole is responsible, and now they have to identify him among the people at the symposium. He goes back to his apartment and experiments with the sample. Viktoria pays him a visit and apologizes, then flirts with him. MacGyver shows her how Mather was killed: someone injected him with a chemical that concentrates in the heart. When the chemical is exposed to a strong magnetic field it turns into nylon, creating a blockage and death. Viktoria admits that Lem could have been responsible, but that he must be working with someone else.
That night, Craig is in bed with Ingrid and mentions MacGyver's theory that Mather was killed. She starts to give him a massage and then activates a hypnotic device that puts Craig in a trance. Ingrid then commands Craig to tell her everything he knows. Once he's fully under, she tells him that MacGyver and Viktoria are the moles and that Craig must kill them both. Lem calls to inform Ingrid that MacGyver and Viktoria have gone back to the exhibition hall. Ingrid assures Lem that Craig is under her control and ready to kill them.
At the exhibition hall, MacGyver has Viktoria examine the security tape for anyone else she recognizes. She doesn't, but they do hear a feedback noise when Mather clutches at his head. Viktoria thinks the sound is familiar but can't place it. MacGyver creates a hypnotic device out of mirrors, wire sculptures, and an ash tray to get Viktoria to relax and tap into her subconscious memories. She's mistrustful and asks MacGyver for a kiss first. He obliges and she says that now she trusts him.
Outside, Ingrid drives Craig to the exhibition hall while Lem knocks out the security guard. Ingrid repeats her instructions to Craig and sends him inside to kill Viktoria before she realizes who Ingrid really is.
Once Viktoria is lightly entranced, MacGyver starts running words by her to gauge her response. She finally recognizes Ingrid and remembers that she was a GRU intelligent operative. Ingrid and Lem come in with Craig, and Ingrid informs them that she's been the mole all along, using the information that Craig revealed under hypnosis. Now she plans to have Craig kill MacGyver and Viktoria, and then replace Pete when he resigns out of grief. MacGyver shoves a TV stand at Craig and then knocks out Lem, while Viktoria fights with Ingrid. Craig recovers and prepares to shoot MacGyver. MacGyver refuses to pick up Lem's gun and tries to get through to his friend. Craig snaps out of it but Ingrid triggers the chemicals, causing him to have a heart attack.
Viktoria punches Ingrid unconscious while MacGyver creates a makeshift heart stimulator out of candlesticks, rubber matting, and microphone cables. He uses it to disrupt the magnetic field and destroy the blockage before it kills Craig. Craig recovers consciousness and thanks MacGyver, and Viktoria congratulates MacGyver on a job well done.