Chic socialite Melanie Daniels enjoys a passing flirtation with an eligible attorney in a San Francisco pet shop and, on an impulse, follows him to his hometown bearing a gift of lovebirds. But upon her arrival, the bird population runs amok. Suddenly, the townsfolk face a massive avian onslaught, with the feathered fiends inexplicably attacking people all over Bodega Bay.
During its return to the earth, commercial spaceship Nostromo intercepts a distress signal from a distant planet. When a three-member team of the crew discovers a chamber containing thousands of eggs on the planet, a creature inside one of the eggs attacks an explorer. The entire crew is unaware of the impending nightmare set to descend upon them when the alien parasite planted inside its unfortunate host is birthed.