Contains two later Professor Challenger stories, "The Disintegration Machine" and "When the World Screamed," which have also been published in other volumes. The remaining two stories contained in this volume are the titular "The Maracot Deep" and "The Story of Spedegue's Dropper." Contents are copyrighted in 1927 and 1928, and the first American edition (Doubleday Doran & Company, Inc.) is copyrighted 1929, as is the first British edition (John Murray).