An evil alien brain, bent on world domination, takes over the body of an atomic scientist, while a "good" alien brain inhabits the body of the scientist's dog and waits for an opportunity to defeat the evil brain.

An ex-Marine, on the lam from a murder charge, hitches a ride with a glamour-magazine photographer, who is travelling cross-country with her principal model. Tensions rise when the women realize the man with them may be a killer.

A giant prehistoric praying mantis, recently freed from the Arctic ice, voraciously preys on American military at the DEW Line and works its way south.