An overextended but seriously exploratory novel that blends two sf themes, alien contact and man-against-nature; its only prior appearance here was as a 1971 paperback. In Kenya, Royce Crawford captures baboons for shipment to the US as experimental subjects. Soon after observing a strange light in the sky, he notes certain baboons who have a curiously intelligent aspect; others mysteriously disappear from their cages; an African worker is killed in suspicious circumstances. So Royce is convinced that an alien intelligence is at work, controlling the baboons--but evidently it's ignorant of local conditions, since the baboons soon sicken and die. Royce attempts, fruitlessly, to communicate with the changed baboons. The station is threatened by a bush fire, then is cut off by torrential rains; desperate, Royce tries to reach a neighboring farmer--but the aliens have taken him over. . . and they soon take his own daughter Barbara. So Royce resolves to make one last attempt to communicate, via compassion: he rounds up the sick alien-occupied baboons and carries them to the alien ship. Rather too low-key (the ironies tend to get lost in the man vs. nature glare), but full of sound anthropological ideas, gracefully and logically illustrated.