Nott, a veteran mountain climber whose Angels Four (1972) recorded his trek up the face of Angel Falls, writes a sort of hybrid National Geographic-cum-Saga prose, but this second Venezuelan adventure is pretty entertaining anyhow. It relates an unsuccessful and nearly disastrous expedition into the world's largest natural shaft, a pit some 400 ft. in diameter and 800 ft. deep, in a strange, geologically ancient, and ecologically isolated plateau in southern Venezuela. Nott and a pair of Venezuelan explorers got into the pit all right, but because of a treacherous overhang they were nearly unable to get out. The scientific uniqueness of the area is subordinated to the hairline-escape aspects, so the title promises more than Nott delivers. But it's tantalizing enough to make one hope that the planned return visit produces another book.