At a nuclear facility in Siberia, MacGyver slips in disguised as a motorcycle messenger. He's looking for political prisoner and poet Yuri Demetri, who is assigned to do dangerous work. MacGyver is there to help him defect and meet with his father in the States. MacGyver tells him to hang tight and then gets on his motorcycle and circles around to Yuri. He gets Yuri on board and drives for a loading ramp, jumping over the good and making good their escape.
In California, MacGyver brings Yuri to his apartment so they can wait while Pete sends them a car so Yuri can meet with his father. MacGyver discovers women's clothing scattered around his living room. Penny Parker emerges from the bedroom wearing a cowboy outfit. She explains that she started a fire during her last job and now she decided to stay with MacGyver... without telling him. She got in by telling the landlord she was pregnant with MacGyver's child. Now she's working as a singing telegraph deliveryperson. Yuri is impressed and introduces himself, saying he'll marry her if MacGyver won't. MacGyver finally gives in and she leaves to deliver a singing telegram, borrowing MacGyver's jeep.
In a suburban home, hitmen Vince and Lyle are in the garage torturing Robert Julian using loud music directed into his eardrums to find out who else knows about him. Julian worked with Derek for 10 years and recently discovered he hired the hitmen. Meanwhile, Penny is in the neighborhood trying to find her customer and hears the music. Figuring that's the party she's there for, she goes to the house and rings the doorbell. The hitmen don't hear her and Julian passes out when his eardrums pop. Penny enters the house while the hitmen figure that Julian didn't tell anyone. Penny comes in and starts singing, much to the men's astonishment. They try to grab her and she runs, locking the door behind her. As she backs up MacGyver's jeep, she slams into their car and then drives away. Lyle gets the license plate and the hitmen tell Derek to find her using his Federal sources and then meet them at a fish cannery after they dispose of Julian's body.
At the Phoenix Foundation, Pete tells Yuri that his father is in New York so he'll join him there the next day. Pete insists he has to stay at the Foundation and asks MacGyver to take him to New York. MacGyver points out that he has a vacation planned but ends up giving in. Yuri is thrilled to have a partner. MacGyver goes back to his apartment just as Penny arrives and tries to explain what happened. She insists they have to go back to the house to rescue the torture victim but MacGyver doesn't believe her. She doesn't remember the address but she remembers how to get there, and MacGyver reluctantly agrees to drive back with her. Penny isn't as sure as she thinks and they drive around the neighborhood. She finds the house next door and barges in, only to realize it's the house next door.
At the cannery, Lyle explains to Vince that he's put a voice-activated detonator on a wheelchair that they'll use to eliminate Estevez, a witness against Colombian drug lords. Derek is their inside man. Derek arrives and provides them with a recording of Estevez's voice. He also tells the hitmen that the jeep is registered to MacGyver and provides his address. Lyle demonstrates the detonator, but it doesn't go off at first. It finally activates, blowing the wheelchair to smithereens. He gives a second detonator to Derek.
MacGyver and Penny go back to MacGyver's apartment where Penny shows MacGyver a scene of her first movie appearance. The TV cuts to a newscast about Estevez's arrival. Penny spots Derek in the background and recognizes him. They check in with Pete, who notes that the Feds are interested in what Penny saw. As they go over the files, Yuri and Penny bond over their artistic abilities. Pete reveals that the government has hired the Foundation to run security, and they found the body of Julian, an agent who was investigating the case.
Derek's superior Jack Larson, who is in a wheelchair. tells him about the Foundation's suspicions and tells Derek to make sure all of the security around Estevez is secure. Derek then goes to see Lyle and Vince and gives them Estevez's location. He warns them that Penny saw him on the news and tells them to dispose of her as well. Derek assures them he's already placed the bomb. Now that they don't need him, the hitmen dispose of Derek on the drug lords' orders then go to get Penny.
As Penny and MacGyver return to MacGyver's apartment, Penny apologizes for getting him into trouble every time she shows up. MacGyver figures she gets into trouble because she cares so much. They go inside and Penny gets a call from someone offering her a commercial audition. They give her a half-hour to get to the set. MacGyver warns her that she can't go out there. Yuri arrives to help protect Penny and explains that he got lost looking for the men's restroom. MacGyver tells Penny to stay and she refuses to listen, and Yuri supports her. Pete calls to tell MacGyver that Yuri's missing. Penny and Yuri leave, unaware that Vince and Lyle are outside. The hitmen load both of them into a van and take them away. MacGyver goes down to get them and sees Penny yell out the back of the van. He grabs a road flare from his jeep and throws it onto the van so he can track it in traffic without being noticed.
The hitmen take Penny and Yuri to the cannery. MacGyver pulls up and tries to find a way in and locates a second-story window. He climbs up and slips in as the hitmen lock Penny and Yuri in a walk-in freezer. After Lyle and Vince say they're going to City Hall and leave, disguised as cleaning crew, MacGyver tries to get into the freezer. He spots the debris from the wheelchair and uses magnesium to heat a pipe and break the lock. Penny and Yuri tell him what they know and MacGyver finds a prototype of the voice-activation detonator. They head for City Hall to rescue Estevez.
Pete meets Estevez as he arrives at City Hall to make a statement. Vince and Lyle, disguised as cleaning crew, get past the security detail and then switch to suits to pass as security men. Larson arrives in his wheelchair, unaware that Derek has attached the voice-detonated explosive to the underside. MacGyver arrives and explains what happened to Pete. They realize that Larson will be next to Estevez when the latter gives his statement. MacGyver arrives and causes feedback in the speakers, interrupting Estevez long enough for Pete to warn him. Penny and Yuri arrive, MacGyver yanks a speaker down on the hitmen when they go for the bombs, and Penny disarms Lyle. Yuri gets the gun and holds Lyle at gunpoint while Pete removes the bomb. MacGyver and Pete thank Penny and Yuri for their help and Yuri figures that real life in America is exciting enough.