An imaginary, utterly absorbing record of the investigations of the Committee on Education, Welfare, and Public Morality of an unnamed state senate into the activities of Mr. Wissey Jones, who has come to the town of Pequot on what he says is urgent defense business.      The hearings develop the suspense of a bizarre trial. It soon becomes clear that Mr. Jones buys for his corporation children of a certain sort, and that he is eager to acquire a ten-year-old named Barry Rudd, who manifests the breathtaking, prickly, sometimes obnoxious, but also deeply moving precocity of a potential genius. The dramatic conflicts exposed during the hearing revolve around the questions of exactly why Mr. Jones's company buys children, and whether he will succeed in buying Barry.              The Child Buyeris a biting commentary on some aspects of American education, on the uses of high intelligence, and on the means of defending democracy. Mr. Hersey makes fine use of the classical weapons of satire--humor and high spirits, sweet dream and nightmare, grotesqueness in the heart of normalcy--to attack not any single theory of education, but the notions that education can be an exact science; that superior minds can be set free by a national crash program; that children can be regarded as weapons; and that talent can be processed and stored for profit and defense.              Although these extraordinary hearings end in a kind of horror, involving the slide into corruption or rascality or apathy of almost everyone connected with them, nevertheless the book leaves in the reader's mind a powerful affirmation--a case for individuality, freedom of thought, integrity, faith in the young, and, above all, a better understanding of human needs in a darkling world.