Getting Inside the Mind of a Shrink : LYING ON THE COUCH by Irvin D. Yalom; Basic Books $25, 400 pages

If Freud or Jung had set out to write a psychoanalytic thriller, I doubt that either one could have come up with a yarn as taut and telling as “Lying on the Couch,” a dazzling psychiatric whodunit by one of the leading theorists and practitioners of psychotherapy in our own times.

Stanford-based psychiatrist Dr. Irvin D. Yalom is an influential teacher and theorist of psychotherapy and author of scientific texts and popular works on the subject, including the best-selling “Love’s Executioner” and “When Nietzsche Wept.” So Yalom brings to his latest work of fiction an authentic mastery of the techniques of psychotherapy and a real genius for showing the reader what is really going on inside the head of a psychiatrist while he or she is shrinking someone else.

The troubled hero of “Lying on the Couch” is a young psychiatrist and analyst-in-training named Ernest Lash whom we follow into the labyrinth of the human mind where both psychiatrists and novelists ply their trades. And Lash is made to experience “that strange paradox of therapy” and novel-writing: “The more unlawful, shameful, dark, ugly stuff you revealed, the more were you rewarded!”

The boogeyman who stalks the pages of Yalom’s book is the shrink who sexually exploits his patients: “Therapist-patient sexual abuse is getting epidemic,” one character is made to say by way of announcing the theme of the book. “Therapists who sexually act out with their patients are invariably irresponsible and destructive.”

Yet Yalom allows us to see more than one therapist-patient sexual encounter in an equivocal light. Indeed, the dirty little secret at the heart of the book--the engine that drives the plot--is the notion that sex is a double-edged weapon that can be used by a disgruntled or disturbed patient against an otherwise innocent therapist.

Indeed, Lash himself is presented as a good-hearted guy who is honorable to a fault when it comes to his own sexuality. “The lady admires you--you act nobly--you don’t get laid,” an old friend scolds Lash when he anguishes over a flirtation with a former patient. “The lady respects you even more and then goes home to bed with the vibrator.”

Along the way, we are given an insider’s view of the politics of psychoanalysis, the scandals that arise in the practice of psychotherapy, and, most intriguing of all, an intimate account of the innermost fears and longings of a psychiatrist at the very moment when he is supposed to be working out someone else’s problems. Given the theme of “Lying on the Couch,” we are not surprised to find Dr. Lash stealing a look at his newest patient’s lingerie--and we are shown how expertly the patient exploits the good doctor’s weaker side for her own evil purposes.

“He was so far out on a limb, so far beyond what traditional technique decreed, so far beyond acceptable clinical practice,” Yalom writes of Lash at his moment of moral crisis, “that he knew he was entirely on his own--lost in the wilderness of wildcat therapy.”

Yalom invokes the novelist’s prerogative of making Dr. Lash’s alluring new patient--who turns out to be the villain of the piece--as detestable as possible. She is a crafty lawyer, a casual adulterer, a faithless friend. Above all, she is depicted as a cynical and calculating seductress with the worst possible motives toward the men in her life, not excluding the psychiatrist whom she has chosen as her victim.

The rule of confidentiality that applies to book reviewers no less than psychotherapists prevents me from disclosing exactly how Yalom works out the cat’s cradle of plots and subplots. But he manages it with such panache that all of his sleight of hand, as a novelist and a psychiatrist, will be forgiven.