The inhabitants of the storybook world of The Great Good Thing are a bit bored - not much has happened since their adventures on the internet (in Into the Labyrinth). But more danger than they've ever faced arrives when the book is stowed away on a space shuttle embarking on a four-year mission to Jupiter. At first the main difficulty is adjusting to life in zero gravity, but when the shuttle misses its re-entry into the Earth's atmosphere, Sylvie and her friends must find a way to help the astronauts survive the additional four years in space. The solution comes in the form of ice collected from one of Jupiter's moons - melting and evaporating the ice provides enough oxygen to sustain the shuttle crew, but it also contains a compound that reverses the ageing process. Soon, the astronauts are only children, and their own lives, and the fate of the characters in the book, lie in the hands of Sylvie, who must reach into their dreams to help them make it back to Earth alive.