Somewhere near India, MacGyver takes a taxi to catch up with a train heading for the border. The engineer finally slows down enough for MacGyver to get on board. The passengers greet MacGyver, who entertains a girl by making a doll for her.
Up ahead, the leader of a local village, Hassan, has his men plant explosives on a trestle.
MacGyver stops at the bar car for a meal and meets Dr. James Grant, a one-armed former doctor who is busy drinking. When another woman, Andrea Collins, tries to help him, he snarls at her. She introduces herself to MacGyver as a State Department courier and realizes he's on a mission. MacGyver explains that he stole evidence of an illegal arms deal and needs to get it to the U.S. authorities to stop a war.
A young couple, Laura and Andy, are arguing about whether they should get married. They've only met recently, but Andy thinks they're perfect for each other and should get married now. Laura isn't so sure. Meanwhile, Dr. Grant comes back and apologizes to Andrea, but bumps into another passenger, Diana Kingman. Diana's domineering mother, Eleanor, insults Grant.
The tribesmen spot the train and blow a horn as a signal. Two tribesmen aboard the train immediately launch a hijack attempt. They accidentally shoot the conductor when he tries to stop them. Grant demands that the tribesmen let him tend to the wounded man, and they reluctantly agree, and Diana helps him over Eleanor's objections. The tribesmen insist that they're there on a matter of justice, not robbery.
Thinking quickly, MacGyver blinds one of the tribesmen by spraying soda water into a bowl filled with water and into the man's eyes. Andrea trips the other man and MacGyver grabs a bottle of alcohol and climbs to the top of the diner car. He douses the roof with alcohol, and when the tribesmen come after him, he sets it on fire, and they're forced to jump. MacGyver proceeds to the locomotive and tells the engineer what happened. The engineer speeds up but the tribesmen ahead realize what happened and blow up the trestle. The engineer stops the train, and Hassan and his men order the passengers out. One passenger, Kramer, hides his briefcase in his pulldown berth. In the locomotive cab, MacGyver rigs the main switch with electricity to shock anyone touching it.
Hassan has his men take the locals away to his village and assembles the Western passengers outside. Dr. Grant gets permission to stay with the conductor. Hassan tells the others that his village built a clinic and paid two Westerners to provide medicine. The medicine was tainted and twenty-six of his people died from it, including his older son. Hassan never met the sellers face-to-face but knows they're on the train escaping the country. He tells the passengers that the must find out who sold the medicine or they'll all starve to death.
The passengers have no idea how to proceed. Andy prepares to escape, telling Laura that he'll go for help. Laura wonders if the authorities won't send a rescue part, but MacGyver warns it will be at least a week until someone notices. MacGyver chats with Andrea and makes a whistle out of a bottle spout, while Diana helps Dr. Grant tend to the conductor. She admits that she's always been strong but plain, and he says he's attracted to her. Grant explains he lost his arm trying to disarm a junkie at his hospital. Diana admits that she wants to be useful to someone and grant assures her that she is as he kisses her.
MacGyver finishes making his whistle, which is pitched high enough so that only animals hear it. He tries it on Hassan's horse as he arrives, briefly upsetting it. Hassan is concerned about the conductor but MacGyver notes that he should have expected someone to get hurt. Hassan talks of how his son demonstrated the syringe containing the medicine to reassure the children, and he was among the first to die. MacGyver warns that Hassan was proud then and is proud now, but killing more people won't bring his son back.
The next morning, Andy tries to sneak away from the train but the one passenger, Kramer, notices him and calls out. Hassan closes in on Andy and MacGyver uses his whistle to distract Hassan's horse long enough to defuse the situation. He gets Andy back inside where another passenger, Webster, accuses Kramer of betraying Andy. Hassan has his men search the train, starting with Kramer's cabin, and they find his briefcase filled with cash. Kramer claims he hid it because he thought the tribesmen were thieves and Hassan admits that they paid in gold, not cash. Kramer is probably a thief or embezzler, but not one of the men who sold them the medicine.
When Hassan talks about pressure, MacGyver gets the idea of making a lie detector out of a blood pressure cuff wired to an alarm clock. He tests it on Andy, who admits that he tried to escape to get help for Laura and that he can't live without her. The lie detector confirms he's telling the truth. Convinced, Hassan orders MacGyver to continue. MacGyver refuses until Hassan explains what he will do with the two men. The villager leader informs him that they'll give the men the same medicine they sold to the village. MacGyver refuses to proceed until Hassan promises to take the men to the next city and turn them over for trial. Hassan agrees but Webster insists he has no authority. MacGyver invites Webster to go next and the man tries to bluff his way through, but the lie detector registers him lying. The assistant conductor is Webster's partner and draws a gun. Hassan wrestles with him and is shot in the hand, and Webster flees.
MacGyver follows Webster to the engine car and tries to sneak around him by throwing a shoe upon the roof to draw his fire. Webster doesn't fall for it and slugs MacGyver, then prepares to back the train up over the tribesmen. MacGyver warns him not to throw the rigged switch, but Webster ignores him and is electrocuted.
Later, the assistant conductor recovers the gold while Grant tends to Hassan's wound. Hassan asks Grant to purchase the correct medicines for them but the doctor warns that it takes more then medicine to guarantee the village's health. Hassan asks Grant to stay as the village doctor, and Diana volunteers to stay and help her new soul mate. Her mother congratulates her on finally striking out on her own and offers to help finance the village's clinic.
Later, Dr. Grant treats Hassan's wound, and Lyman returns the gold. Hassan asks Grant to buy the proper medicines, but the doctor says he needs an actual doctor. MacGyver points out that Hassan wants Grant as a doctor. Grant warns that he can't handle it single-handedly, but Diana volunteers to stay with him. Her mother tells her it's about time and offers her help if they need it. The tribesmen bring the local passengers back and the little girl gives her doll back to MacGyver, who says Grant and Diana have a lot to look forward to.