The Invaders follows architect David Vincent, who accidentally witnesses the landing of a spacecraft from another galaxy. After discovering that extraterrestrial beings have begun infiltrating human society by assuming human form, he attempts to warn a skeptical public. Because the aliens are physically indistinguishable from humans—except for a slight physical deformity in their pinky fingers and an inability to regenerate—Vincent finds himself constantly discredited and labeled as delusional. As the series progresses, Vincent travels across the United States, gathering evidence and attempting to expose the alien conspiracy. He eventually gains the assistance of wealthy industrialist Edgar Scoville, who provides resources to help fight the silent invasion. The show is characterized by its paranoid atmosphere, highlighting the struggle of one man against an overwhelming, hidden enemy that seeks to prepare Earth for a full-scale takeover.