When Gwendy Peterson was twelve, a mysterious stranger named Richard Farris gave her a mysterious box for safekeeping. It offered treats and vintage coins, but it was dangerous. Pushing any of its eight colored buttons promised death and destruction. Years later, the button box reentered Gwendy's life. A successful novelist and a rising political star, she was once again forced to deal with the temptation the box represented. Now, malignant forces seek to possess the button box, and it is up to Senator Gwendy Peterson to keep it from them at all costs. But where can one hide something from such powerful entities?

In Gwendy's Final Task, master storytellers Stephen King and Richard Chizmar take us on a journey from Castle Rock to another famous cursed Maine city to the MF-1 space station, where Gwendy must execute a secret mission to save the world. And, maybe, all worlds.