MacGyver is in Elm Creek, Minnesota working on a hot spring project when he spots a glowing saucer-like object floating above a field. The electrical systems in his car go out and he coasts to a halt. A man in a black suit is watching it and asks MacGyver what he thinks it is. MacGyver moves in and spots a figure in a silvery suit and helmet wielding a metal implement. The figure approaches MacGyver and then clubs him unconscious.
Later, MacGyver wakes up and discovers that the glowing object, the figure, and the black-suited man have all disappeared. MacGyver walks back to his car past the electrical high-power lines in the vicinity. He notices a cabin nearby with no lights and walks over to it. As he walks up to the porch, a small boy runs out and MacGyver manages to capture him. The boy, Tommy Wiley, says he doesn't live there and previous residents just left one night. Tommy wonders if MacGyver is an alien. Once he's convinced otherwise, Tommy admits he saw the saucer as well and heads for home. MacGyver asks to use his family's phone and Tommy warns that his dad John doesn't like strangers. MacGyver persists and Tommy takes MacGyver back.
John is preparing supper when Tommy and MacGyver arrive. When they say they saw lights, John says he was busy tending to his sick wife, Sarah, and didn't see any lights. He offers MacGyver the use of his phone to call a tow truck. As MacGyver makes the call, Tommy starts to whisper something but his mother calls him away.
The next morning at his motel, MacGyver meets the man in the black suit. He introduces himself as Phil Sternwise, a vacuum cleaner salesman. He says he didn't see anyone hit MacGyver and wonders if MacGyver believes in flying saucers. MacGyver admits he chalks up UFO sightings as natural phenomena but Phil isn't convinced. He tries to sell MacGyver a vacuum cleaner without success and wishes him well hunting natural phenomena.
At the garage, the mechanic, Parnell, reveals that the car's generator is burned out even though MacGyver installed it just a month ago. Parnell admits that he's read about UFOs and they disrupt electrical equipment. He warns that electrical malfunctions are the first sign of an alien invasion but MacGyver is less than impressed. He goes out to the field with a Geiger counter and finds a giant circle burned into the dirt. There are smaller holes burned into the ground and they emit radiation. As MacGyver notices the high-power wires, John shows up to say that MacGyver's trespassing and that he's in charge of the property as the caretaker. The sheriff arrives and notes that almost everyone in town saw the lights. He knows that MacGyver is a scientist with the Phoenix Foundation on the hot springs project but figures the UFO is the result of kids playing a prank. John isn't happy and stalks off. The sheriff notes that the hot springs power plant is more important than chasing aliens and MacGyver takes his point.
When MacGyver goes back to his car, he finds Tommy hiding in the back. The boy says that there are strange people from the spaceship and they've told his dad they're going to take him to another planet. John wants to take his wife with them because they can cure disease and she has cancer. Tommy doesn't want to go and plans to run away in the back of MacGyver's car. MacGyver figures that the trip will cost a lot of money and Tommy admits it's worth anything. The aliens talked to his father that morning and the Wileys are going that night. Tommy tells him that he followed the aliens and they're staying in a trailer at the campground.
MacGyver goes to the campground and finds the aliens' trailer. He takes note of the Illinois license plates as a man emerges. He introduces himself as Ray Rigel and asks what MacGyver is really there for. He talks of love and joy and offers to give it to MacGyver. However, his wife Dawn emerges and warns that MacGyver isn't a believer. The couple goes back into their trailer and MacGyver leaves.
In Elm Creek, the sheriff visits MacGyver as he analyzes the dirt from the saucer site. It contains napalm and MacGyver figures the Rigels faked the landing site. He tells the sheriff that the couple is conning the Wileys into turning over their life savings. The sheriff refuses to ask John if he's planning a trip to outer space but agrees to check the Rigels' license plate. However, he tells MacGyver to steer clear of the Wileys.
The Rigels go to the Wiley farm and John talks to them privately. They tell him that their planet is perfect and John warns them that MacGyver has been prowling around the landing site. The Rigels say that their superiors will cancel the departure unless John "neutralizes" MacGyver.
MacGyver sneaks into the Rigels' trailer and searches the place. He finds a jar containing radioactive black rocks and takes some samples. The Rigels pull up and MacGyver has nowhere to hide. However, Phil shows up outside and tries to sell the Rigels a vacuum cleaner. When they're distracted, MacGyver sneaks out. As the Rigels go inside, MacGyver turns back only to discover that Phil has mysteriously disappeared.
The sheriff checks in with MacGyver, who has replicated the fake UFO landing using electro-chemical plasma. He figures the Rigels released ammonia fumes that interacted with the high-power lines and a generator from their trailer to create the UFO. They then salted the area with low-grade uranium and used a flame-thrower. The sheriff reveals that the Rigels are from Orion, Illinois. MacGyver explains that Orion and Rigel are astronomical bodies but the sheriff doesn't believe it. He shows MacGyver an arrest warrant: John has filed trespassing charges with the county attorney. MacGyver denies it but the sheriff has no choice but to arrest him.
The Rigels thank John and Sarah for neutralizing MacGyver and are more than happy to take their money so the Wiley can prove they are divesting themselves of material goods. With a little prodding from Sarah, John agrees to have the money that night. They are all unaware that Tommy is listening in.
At the jail, MacGyver admits he doesn't have the money to post bail and figures the Rigels will be conned that night. Phil appears in the lobby and posts bail for MacGyver. Outside, MacGyver demands answers but Phil insists he's just a concerned bystander and the Wileys almost bought a vacuum cleaner from him once. When MacGyver points out its weird how he keeps showing up where he's needed, Phil says he's just a good salesman.
Tommy rides his bike to the Rigels' trailer and deflates one of their tires. Ray catches him and they lock him in their trailer.
That night, MacGyver goes to see John and show him his UFO demonstration. John reluctantly gives him a chance but Sarah interrupts, demanding to know where Tommy is. She thinks that MacGyver is keeping Tommy from them from leaving. MacGyver tries to explain but Sarah is despondent, insisting that they're in debt and there must be a place where bad things don't happen to good people. John sides with her and orders MacGyver out at gunpoint. As he goes, MacGyver notices the power lines overhead. He drives around to the back of the property and then approaches the power line posts. He goes inside the nearby building and finds some barbed wire, but is interrupted when Phil appears behind him and says he's there to help.
The Rigels pull up outside while MacGyver and Phil hook up the barbed wire to the power posts. The "alien" couple tells the Wileys that they have Tommy in their trailer and they should leave him alone until they're ready to go. John, skeptical, says he'll give them the money once they're on the ship. Dawn objects and John realizes something is going on. He demands they release Tommy and Dawn draws a gun on them. John turns over the money and is forced outside with his wife. MacGyver starts rubbing the barbed wire on a block of salt to turn his demonstration into a distraction. Meanwhile, the Rigels lock the Wileys in the barn and set it on fire with their flame-thrower. MacGyver and Phil throw their lengths of barbed wire onto the power lines above them, creating a fake UFO. The Rigels chase after MacGyver and Phil, who split up. Phil knocks out Dawn but Ray corners MacGyver. Phil appears behind him and Ray fires at him, only for the igniter on the flame-thrower to short out. MacGyver knocks Ray unconscious and looks up only to discover that Phil has vanished again. The Wileys reveal that someone unlocked the door and put out the fire, but they have no idea who Phil is.
Later, the sheriff confirms they've found enough evidence to put the Rigels away. The Wileys thank MacGyver, who tells Sarah that they're coming up with treatments all the time and she shouldn't give up hope. The sheriff's deputy discovered that Phil checked out of the hotel that afternoon. John remembers that Phil came out just before the Rigels showed up and tried to sell them a vacuum cleaner. Tommy arrives and tells them there's something outside. They go out and see a large flying saucer departing. John wonders if it's more of the electroplasma but MacGyver has to admit that this flying saucer is moving and there are no power lines. MacGyver has to admit he isn't sure what it is.