As a reader of many (sadly forgotten) Jerry Sohl novels, "Night Slaves" is one of my favorites, but it is also one of his most disturbing. Sohl's interest in psychology is very prevalent in this book, but he nevertheless shows the limits of that brain science for strong dramatic effect. The plot is about a man who is in therapy, telling his psychiatrist about a town that he and his wife recently visited where two super-powered humanoid aliens kept the residents under their mental control while they repair their spacecraft. The psychiatrist does some investigating of his own, only to find himself falling in love with the man's wife (who has no memory of the strange events the man recounts). But there is evidence that there are strange things going on in the town AND that the man is mentally disintegrating. What is really going on?
This novel is one side of a coin when it comes to a humanoid alien race possibly interacting with humans. The other side is Mr. Sohl's earlier novel, "The Transcendent Man" a far lighter, but still entertaining, novel about a man who believes he has encountered super-powered humanoid aliens, much to his dismay.