Marjorie Daw is a librarian, and takes her job - and indeed the truth of words - very seriously. She doesn't know it, but her world and ours - Roundworld - is in big trouble. On Discworld, a colossal row is brewing. The Wizards of Unseen University feel responsible for Roundworld (as one would for a pet gerbil).

The fantastic first book in the Sunday Times bestselling Science of Discworld seriesWhen a wizardly experiment goes adrift, the wizards of Unseen University find themselves with a pocket universe on their hands: Roundworld, where neither magic nor common sense seems to stand a chance against logic.