The novel "The Thing That Walked in the Rain" is a jungle adventure novel. A Professor working in the jungles of Nicaragua suddenly goes missing. Professor Charles Mabrey, explorer and naturalist, had undertaken the leadership of the expedition for the purpose of clearing up the mystery surrounding the strange disappearance of his friend and colleague, Dr. Fernando de Orellana. And he made it plain that he did not, for one moment, countenance the weird, incredible story which linked that disappearance with the traditional mystery of the extinct volcano. It was his frank and unalterable opinion that the doctor had been murdered by the natives, and that they had invented the outré story of a man-eating monster inhabiting the crater-lake purely to shield themselves from punishment. But as the party searches deeper into the woods, they are about to make a shocking discovery…