This is one of the works of fiction published during Doyle's life. Published in 1929, only a year before the author's death, this short novel amply demonstrates that Doyle still retained all his great abilities as a spinner of riveting yarns, even in his twilight years. The book concerns Maracot's exploration of the world beneath the sea. Maracot and his companions find themselves stranded on the ocean floor, and discover a very unexpected world, in fact a civilisation, deep beneath the waves. They are introduced to a remarkable and ancient society that expands their knowledge of human civilization's history and then even more so, their understanding of planes of existence.Their visions of the future of humanity possess an optimism and a romance that simply isn't possible to writers today.