A hospital administrator and a former Green Beret join forces to try to aid a group of Montagnards, a pro-American people who were trapped in Thailand following the Vietnam War.

When a comet passes close to the earth, machines all over the world come alive and go on homicidal rampages. A group of people at a desolate truck stop are held hostage by a gang of homicidal 18-wheelers. The frightened people set out to defeat the killer machines ... or be killed by them.

Mark Kaminsky is kicked out of the FBI for his rough treatment of a suspect. He winds up as the sheriff of a small town in North Carolina. FBI Chief Harry Shannon, whose son has been killed by a mobster named Patrovina, enlists Kaminsky in a personal vendetta with a promise of reinstatement into the FBI if Patrovina is taken down. To accomplish this, he must go undercover and join Patrovina's gang.