Involves a new high-speed supertrain making its inaugural run across the American Southwest when a meteor strikes the Earth in close proximity to the rail line the train is using. The train’s journey is interrupted as police investigate the crash. At that time, a tiny creature boards the halted train and begins to grow and devour the train’s conductor. The monster also damages the train’s drive mechanism which causes it to become a runaway. If that isn’t bad enough, the creature multiplies shortly after feeding.