Format: Global Grey free PDF, epub, Kindle ebook
Pages (PDF): 31
Publication Date: 1928
A short story; the fourth in the Professor Challenger Series. Professor Challenger, with the help of Mr Edward Malone and Mr Peerless Jones, drills into the earth until he reaches the mantle, convinced that it is a sentient being, akin to an echinus, and that by doing so he will be the first person to alert it to mankind's presence.