One (white) man expedition to South American jungles for the purpose of giant-ant research. The author acquires an English companion, and finds himself done up in searches for diamonds and gold as well. They have the usual -- and some unusual --adventures, explore giant waterfalls, fly over jungles, land on a sand-spit from which they are rescued by natives, meet natives who have never before seen white men, and eventually ascend Mount Roraima, a plateau which might have presented strange remnants of prehistoric life -- but did not. The ant material makes an interesting objective, the adventures, while not hair-raising, are good reading, and the attitude, if often openmouthed wonder, is appealingly enthusiastic and appreciative.