Gwendy is 12 years old and lives in Castle Rock, Maine. In 1974 every day, she climbs to the top of the stairs referred to as Suicide Stairs. One day she meets a stranger, Richard Farris, waiting for her at the top of the stairs. The man is wearing a small black hat, and even though she has never met him, he seems to know a lot about her and some of the things she wants.

Farris gives her a special wooden box with a lever attached; when you pull it, you either get unique chocolates that help you lose weight or silver dollars. The box has eight buttons. Using some of them causes good things, even losing weight which she needed to do.

When she eventually pushes one of the other buttons, terrible things happen. She also learns that one of the buttons, which is black, when pressed, will cause cancer. The story takes us through Gwendy’s childhood, high school, and beyond; the story tells of the time she spends protecting this box and how she learns of its positive and negative influences on the world she lives in.