A trio of aliens, dressed as "hoodlums" in black leather jackets, arrive in a small town, look to eradicate all life on Earth so their kind can expand on a new planet. However, one of the aliens falls in love with a local girl and is hesitant to go along with his friends' plans and ultimately tries to talk her into leaving town with him.

Computer programmer James Elwood is called in to fix the world's most powerful computer – codenamed Agnes – and soon turns to Agnes for help in wooing a coworker named Millie. However, Agnes soon becomes jealous of James's feeling toward Millie and promptly begins sabotaging their relationship.