When Earth passes through the tail of the rogue comet Rhea-M, every machine on the planet — trucks, lawnmowers, arcade games, vending machines — suddenly and inexplicably comes to murderous life. A ragtag group of survivors, including paroled short-order cook Bill Robinson and a hitchhiker named Brett, are besieged at the Dixie Boy Truck Stop in North Carolina, where a fleet of eighteen-wheelers circles relentlessly and forces the humans at gunpoint to fuel them. Bubba Hendershot, the tyrannical owner of the diner, reveals a cache of weapons in an underground bunker, giving the group a fighting chance against the mechanical marauders. The survivors make a desperate bid for freedom, attempting to reach the waterfront and escape by boat while battling the relentless machines at every turn. The film closes with a title card revealing that an alien spacecraft — presumably controlling the machines — was later destroyed by a Soviet Union military satellite, bringing the nightmare to an abrupt and absurd end.