When Orville Mouse rescues an errant windblown hat on his way to work, he soon discovers the hat's shadow is not behaving as it should. While attempting to discover the cause of this curious phenomenon, Orville and his best friend Sophia Mouse uncover a terrifying secret and are pulled into a desperate race to prevent the imminent destruction of uncountable parallel worlds.With help from their old friend Proto the Rabbiton, Astromechanist Madam Molly, the Mad Mouse of Muridaan, a robotic museum curator named Copo, a pair of gigantic vacationing insects, a ghostly Thaumatarian engineer, the vaporous Others, and the simmering Forest of Thorns, the two stalwart adventurers must retrace the path of a centuries old adventurer named Haukesworth Mouse to the lost world of Tectar and a terrifying confrontation with Mendacium the Dark Wizard in the dank and dismal dungeons of the infamous Castle Caligari.