When Dr. Tom More is released on parole from state prison, he returns to Feliciana, Louisiana, the parish where he was born and bred, where he practiced psychiatry before his arrest. He immediately notices something strange in almost everyone around him: unusual sexual behavior in women patients, a bizarre loss of inhibition, his own wife's extraordinary success as bridge tournaments, during which her mind seems to function like a computer. With the help of his attractive cousin, Dr. Lucy Lipscomb, Dr. More begins to uncover a criminal experimentto "improve" people's behavior by drugging the local water supply. But beyond this scheme are activities so sinister that Dr. More can only wonder if the whole world has gone crazy -- or he has . . .