AFTER ROBIN COOK's first book, The Year of the Intern , failed to become a best seller, Cook set out to discover why. If he was going to spend time writing books, people were, damn it, going to buy them. He read dozens of best sellers, concentrating on the thriller genre. He analyzed plots; took, I would guess, a passing glance at character development; and decided on a formula which combined medicine, murder, and a lot of suspense, sort of a modern version of "Lincoln's Mother Doctor's Dog." The resulting book, Coma , did, in fact, become a very best seller. Which proves, to my satisfaction, that Robin Cook is a clever fellow.

In his next book, Sphinx , he left out the materia medica and, though the book sold well, its success did not equal that of Coma. And, of course, Cook learned a lesson from that experience: don't mess with a successful recipe. Into his new book, Brain, he has thrown in all the ingredients that worked so well in Coma. The action, except for one "chase" scene (which shoud be nicely filmable), takes place almost entirely in a hospital. There are some very nasty doctors, one very heroic doctor, a beautiful, sexy female resident physician, and a plot with enough twists and turns to satisfy any reader. In fact, the similarities between the two books are so great that Brain could accurately be subtitled "Son of Coma"; or, perhaps more appropriately, "Clone of Coma."

I don't want to reveal too much of the plot (always a problem when reviewing a suspense story), but I think it's fair to say that research in artificial intelligence is a keystone in the book. The hero is a neuroradiologist, who is working with a research scientist, developing a computer that will read X-rays as well as, or better than, a radiolgist (incidentally, not an inconceivable goal; computers already read electrocardiograms as well as many cardiolgists). The computer identifies some peculiar changes in skull films, abnormalities not noticed by the neuroradiolgist who first read the films. The patients are all young college women who have recently been treated at the dingy university gynecology clinic. These girls all disappear, except one who dies in the course of a brain operation. When Dr. Martin Philips, the hero of the story, discovers that someone has gone to the morgue and removed the brain of this unfortunate victim, even though -- supposedly -- no autopsy was done, it's obvious that there is skullduggery going on (if you'll excuse the pun).

Shall I say, "I couldn't put the book down"? Why not? It's true. Even though Brain is low-grade formula fiction, close to Nancy Drew and The Hardy Boys than to the works of John Le Carre or Robert Ludlum, it is -- to pile on another cliche -- a damn fast read. It will not be a succes d'estime, but it will be a very popular success. I expect that in the not-too distant future, we'll have "Liver," or "Kidney," or possibly "Lung." Robin Cook has discovered his own little gold mine, and there are enough organs in the body to keep him working for a long time to come.

M.D., a first novel by Dr. Neil Ravin, is a book I greatly enjoyed. Although it contains the standard disclaimer -- all characters, places, incidents, etc. are fictional -- there isn't the slightest doubt that "Manhattan Hospital" is New York Hospital, that "Whipple" is Sloan-Kettering, and that "Manhattan Medical School" is Cornell. In fact, the nickname the book's residents and interns apply to Manhattan Hospital is the "White Tower," the name by which New York Hospital has been called at least since 1953, when I began my surgical training at the Cornell Surgical Division of Bellevue Hospital, sort of a ne'er-do-well cousin of the great White Tower itself.

M.D. is the story of 18 months in the life of Bill Ryan, one year of internship, six months as an assistant resident. He lives in a comfortable townhouse, owned by the grandfather of his roommate, Arch, a young lawyer. Ryan is a dedicated doctor, but not a pompous one. He doesn't make a big show of being a caring person; he just works, all day -- and all night if necessary -- to help his patients survive. He gets angry at the hospital bureaucrats who demand, for example, that death certificates all be signed with black ink; he insists on signing in red, green and other colors just to upset everyone. Foolishly, of course; no doctor will ever defeat the hospital's bureaucrats.

Ryan also learns, as do all interns, that it's not necessarily the best-educated or highest-paid people who make a hospital work. For example, "The clerk runs the floor. If the clerk is a turkey, it doesn't matter how good the nurses, doctors or patients are -- the floor doesn't work. The clerk gets the blood tubes set up for the morning drawing, sends them to the various labs after they are filled, schedules patients for the tests doctors order, set up X-rays, gets escort service to take patients to tests, and does anything the nurses don't have time for or don't want to do." That's the ward clerk, all right, and it brings back memories of Miss Scott, a ward clerk at Bellevue for the seven years I was there. She was a legend in her own time. She made that ward work, despite a head nurse who was all smiles but constantly confused.

Ryan has woman trouble. Not a lack of women; a surplus. There's Hope, a cute, bright nurse, who loves to take showers with him; Diana Hayes, married, director of diagnostic cardiology, who keeps Ryan continually off balance as she alternates between being his professor and his lover; and Caroline, a young girl with Hodgkins's disease, who falls in love with him.

Ryan, like all interns, has much to learn, and he does -- from the residents, the nurses and, most of all. the patients. He has mastered enough of the science of medicine to get by, but he needs experience in the art. He gets angry at patients who abuse themselves. "'But that's human frailty. You have to accept frailty, if you're going to treat suffering,'" said Brigid [a nurse], a little perturbed. 'It's called compassion.'

"'I call it abuse. I wish that alcoholic had some compassion for me. Maybe he'd let me sleep through the night.'

"'Ryan,' laughed Brigid, blowing smoke in his face, 'You're such a hard-ass. But a hard-ass is still an ass.'"

Why did I like this book so much? Because it rings true. The interns, the residents, the attendants, the patients, the long hours, the depressing illnesses, the suffering, the triumphs, the joy -- every bit is the real thing. It made me nostalgic for my days and years at Bellevue; I don't suppose I could really live through them again, or would want to try, but Neil Ravin stirred memories in me of experiences I had all but forgotten. The medical advances of the last 20 years are awe-inspring, but finally the doctor-patient relationship is still one on one.

For anyone who wants to know what it's like to be a doctor at the beginning of a career, idealistic, energetic, dedicated, frustrated, without any concerns about fees, referrals, cars, golf club memberships, government regulations, the FDA -- all the things that, later, clutter up a doctor's life -- this is the best book I've read in years.