Description
A family of aliens on a dying desert planet search 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 a government base with their ability to manipulate electricity and destroy anything they touch. While most of the family runs off into the desert, the smallest alien breaks away and hides in a passing minivan occupied by single mother Janet Cruise and her two young sons (wheelchair-using younger son Eric and elder son Michael) who are moving to a new home near Los Angeles following the loss of the family patriarch. Shortly after the move, Eric suspects the alien's presence. The next morning, he finds that the creature has trashed most of the house and learns its identity, but Janet blames both him and Michael for what has happened. After noticing the creature, Eric tries to catch up to him, but ends up sliding down a hill and falls into a lake, where he nearly drowns, but is rescued by the alien. Eric is not believed at all when he tries to tell his family about the creature's actions.
Later that night, he sets a trap with the help of his new friend, Debbie, who had also seen the alien. The two trap him inside a vacuum cleaner, which malfunctions and causes the entire neighborhood to suffer a power surge. After the alien is released, Michael now believes Eric, but it leaves before Janet can be convinced. Eric's behavior towards the alien, which he names MAC (short for "Mysterious Alien Creature") changes after he fixes all of the damage he caused 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 begin spying on the Cruise residence. Eric disguises MAC as a teddy bear 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 on his wheelchair. After Wickett and Zimmerman chase them through a nearby neighborhood and shopping mall with additional help, they are rescued by Michael and Courtney. Janet, having witnessed the chase while in the mall, catches up to the agents and inadvertently learns from Wickett that MAC is indeed real.
Eric, Michael, Debbie and Courtney decide to help reunite MAC with his family, who are lost in the desert without sustenance. Following MAC's directions, they travel to the mountains on the outskirts of Palmdale, where they find MAC's dying family and rejuvenate them with Coca-Cola. The group stops at a gas station and goes to a nearby supermarket. The restless aliens climb out of the minivan and enter the store, causing a panic. After MAC's father steals a gun from a security guard, the police arrive and a shootout takes place in the parking lot, which ends with an explosion destroying the supermarket 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 Eric's life, the United States government grants MAC's family American citizenship, with the Cruise family and their neighbors, as well as Wickett and Zimmerman, in attendance at the ceremony. MAC's family, in Earthling clothing, drives off in a pink Cadillac, and MAC blows a chewing gum bubble that reads "We'll be back!"