Lonely nerd Seymour Krelborn works in Mushnik's flower shop on skid row, enduring constant criticism from Mr. Mushnik and hiding his crush on co-worker Audrey. When Seymour finds an odd, unidentified plant, he names it after Audrey. But the plant doesn't use soil, water, and sunshine like other plants, and is wilting until Seymour accidentally discovers that it needs blood. Audrey II becomes a neighborhood attraction, bringing business to the shop and celebrity to Seymour. The now enormous Audrey II talks to Seymour when no one is around. It gets hungrier every day and Seymour is getting weak from feeding it his blood. So when it presses him to kill for him, Seymour brings back the body of Audrey's abusive boyfriend. Audrey and Seymour reveal their mutual love for each other, but their happiness is threatened when Mushnik accuses Seymour of murder. So Audrey II protects his meal ticket by eating Mushnik. Guilt-ridden Seymour has switched the menu to ground chuck when he learns that his plant is really a space alien out for world domination. After a violent fight, Seymour electrocutes the menace, and he and Audrey marry and move to the suburbs.