Movie star Roxy Carmichael is abandoning the bright lights of Hollywood, Calif. and returning to her small Ohio hometown - at least long enough to dedicate a city building. And now the whole town of Clyde is bracing for Carmichael's return, most of all her now-married old flame Denton Webb and troubled teen Dinky Bossetti. An orphan with few friends, Dinky is convinced that Carmichael is her birth mother, and that the actress will reclaim her when she returns.
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.