When the Impossible Postal Express magically arrives to collect Suzy, she sets off on her most difficult delivery yet. A mysterious talking book is stealing words and causing chaos across the whole of the Impossible Places!

The book must be returned to a city that's been lost for thousands of years. But without a map to get there, Suzy and Wilmot's journey plunges them into grave danger, deep beneath the ocean. And with time running out, it might not just be the knowledge in the Impossible Places that is lost for ever - Suzy and Wilmot could be too...