A paranoid, secretive surveillance expert has a crisis of conscience when he suspects that a couple he is spying on will be murdered.

During the Vietnam War, Captain Willard is sent on a dangerous mission into Cambodia to assassinate a renegade colonel who has set himself up as a god among a local tribe.

After a space merchant vessel perceives an unknown transmission as a distress call, its landing on the source moon finds one of the crew attacked by a mysterious life-form, and they soon realize that its life cycle has merely begun.