| Director | Stewart Raffill |
|---|---|
| Budget | $13 million |
| Box office | $6.4 million |
A family of aliens on a dying desert planet searches for subterranean water to drink through a straw. A NASA research probe lands and begins taking atmospheric samples via a suction device. The aliens are accidentally sucked into the apparatus, and the probe returns to Earth. The aliens escape from a government base with their ability to manipulate electricity and destroy anything they touch.
While three of them run into the desert, the smallest one hides in a passing minivan occupied by single mother Janet Cruise and her two sons (younger son Eric, who uses a wheelchair, and elder son Michael), who are moving to a new home near Los Angeles following the loss of her husband. Eric finds that the alien has trashed most of the new house and sees the being, but Janet blames him and Michael for what has happened. After noticing the alien outside, Eric tries to catch up to him but rolls down a hill in his wheelchair and falls into a lake, where he is rescued by the alien.
Later that night, Eric sets a trap with the help of his new friend, Debbie, the girl next door who has also seen the alien. They trap him inside a vacuum cleaner, which malfunctions and causes the neighborhood to suffer a power surge. Eric's behavior toward the alien, who he names Mac—an acronym for "Mysterious Alien Creature" (MAC)—changes after the extraterrestrial fixes the damage to the house and leaves behind several newspaper clippings that Eric believes are an attempt to communicate.
Meanwhile, FBI agents Wickett and Zimmerman track Mac down and spy on the Cruise residence. Eric disguises Mac in a teddy bear suit and takes him to a birthday party at a local McDonald's, where Debbie's older sister, Courtney, works. Wickett and Zimmerman follow, but Mac starts a dance number as a distraction and escapes with Eric. After Wickett and Zimmerman chase them, Eric and Mac are rescued by Michael and Courtney. Janet, having witnessed the chase, catches up to Wickett and Zimmerman and learns that Mac is real.
Eric, Michael, Debbie and Courtney decide to reunite Mac with his family, who are lost in the desert. Following Mac's directions, they travel to the mountains on the outskirts of Palmdale, where they find his dying family and rejuvenate them with Coca-Cola. The group goes to a supermarket to buy more Coca-Cola for the aliens. The restless aliens enter the supermarket, causing a panic. After Mac's father steals a firearm from a security guard, the police arrive, and a shootout takes place in the parking lot, which ends with the supermarket being destroyed in an explosion and Eric being killed by a stray bullet.
Once Wickett, Zimmerman and Janet arrive by helicopter, Mac and his family use their powers to revive Eric. For saving his life, the United States government grants them American citizenship, with the Cruise family and their neighbors, as well as Wickett and Zimmerman, at the ceremony. Mac's family, dressed like Earthlings, drives off in a pink Cadillac, and Mac blows a gum bubble that reads "We'll be back!"