A mysterious murder brings together three young men, John, Jack and Charles, who do not know each other, on a rainy night in London during the First World War. A strange little man named Bert claims that they are now the custodians of the Imaginary Geography - an atlas of all the lands that have ever existed in myth and legend, tales and tales. According to Bert, you can get there on his ship, the Blue Dragon, one of seven ships that can cross the Boundary between Worlds on the way to the Archipelago of Dreams. Pursued by strange and terrifying creatures, the comrades leave London aboard the dragon ship. Journeying into the heart of imagination, they must learn to overcome their fears and trust each other if they are to defeat the forces of evil that threaten the fate of two worlds. Together they will make a great journey, during which the reader will find many clues leading to the unexpected revelation of the legendary authors who will one day become the guardians of the Geographica.