THERE is a Puritan branch of escape literature which allows us to feel virtuous while eating our bonbons. In these books the characters play out their plots against a background of accurate historical detail or share with us some arcane and technical knowledge. We are not just escaping; we are learning something new.

Five of the six books reviewed here are for those who like to learn while they yearn. Which you choose depends on what it is you'd like to know. NO GREATER LOVE

By Frank G. Slaughter. Doubleday. 252 pp. $15.95

IF, WHEN SOMEONE announces that "Cyclosporin was just another drug discovery. . . until somebody noticed that it attacked the lymphocytes in the body and put two and two together," you go rigid with boredom, No Greater Love will not do it for you. Here the doctors are gods, with Dr. Paul Fraser "approaching 70" and "tall, craggy-faced and vigorous," Dr. Liz MacGowan, "a lovely red-haired young woman" and her boyfriend, Ted Bronson, "six-feet two with the lithe grace of the college athlete he'd been . . . the epitome of a successful young surgeon." Oh, there are close calls, as the plot pushes its way through trite dialogue and into the morning headlines, but the doctors always triumph.

There is a brain-dead princess whom Liz must keep alive as an incubator for the princess' baby, the possible heir to an Arab emirate which is, of course, on the verge of revolution; there is a federal prosecutor shot by the big-time drug pushers he is pursuing. The prosecutor needs a liver transplant, and Dr. Ted is just the man to do it. "While he was in the abdomen, he took the pancreas, too, and afterward, one of the cardiac surgeons removed the heart. It's in Atlanta, by now, going into the chest of a young mother who was dying of rheumatic heart disease. The Department of Ophthalmology took both eyes for corneal transplant and the octologists were happy to get out two sets of ossicles."

Man as Tinker Toy and the doctor as master builder -- it is thoroughly modern medicine and the only thing it has failed at is getting the cliches to clot. GABRIELLE

By Agnes Short Beaufort. 238 pp. $15.95

IN Gabrielle, we learn about grapes and the dread philloxera, the American plant louse which, in the 1870s, made its way to Europe and devastated the French wine industry. Eventually the industry recovered by grafting French vines onto resistant American root stock, but it takes a vine four to five years to reach full harvest and during that time, poor Gabrielle, a low- born Englishwoman who has married a high- born Frenchman, must try to save the family fortune. Her husband, Paul de Chardon, prefers drinking brandy to making it, and it is Gabrielle who must learn (and teach us) about grafting and root stocks, about the cigareur and the maladie rouge, about pruning and pressing and the joys of la vendange, when the grapes are harvested and the work is rewarded.

Before Gabrielle gives her life to the grape, she has a brief flirtation with art and artist: "'Impressionists,' they call us, meaning a scathing insult, but we wear the title with defiance, as the glorious truth."

As the book nears its end, the artist reappears, offering Gabrielle a chance at love and freedom. But the grapes have wrapped their tendrils around our poor heroine, and here the book diverges from most escape literature by denying us a happy ending and making us settle, with Gabrielle, for the moral uplift of having done the right thing. THE LANDOWER LEGACY

By Victoria Holt. Doubleday. 374 pp. $15.95

IT is standard practice in romantic fiction to toss the heroine out into a cold, cruel world. She is orphaned and passed into the clutches of an evil uncle, or married to a man who whisks her off to a castle on the moors where he changes from a loving husband into a sullen monster. Oh woe! But I'm afraid it is necessary since one does not get to be a heroine by sitting at home and sewing a fine seam.

Victoria Holt has cast out many a heroine and done it very well indeed, so it is no surprise when Caroline Tressidor in The Landower Legacy finds herself "snatched from my home, from my sister, from my parents . . . everything was going to be new now, and there is always something alarming about the unknown."

It is the time of Queen Victoria's Golden Jubilee, and the events of that fateful day send Caroline into exile at Tressidor Manor in Cornwall. Caroline finds several suitors but only one true love. Alas, it is not to be. Or at least not until Caroline and Paul have worked their way through a 370-page obstacle course containing a broken engagement, an unfortunate marriage contracted to save the family estate, severl deaths and a birth or two, disappearances and a wonderfully fortuitous murder. The reader gets value for money in this book by a very competent escape artist. MAGIC FLUTES

By Eva Ibbotson. St. Martin's. 255 pp. $12.95

THE FORMULA begins to blur in Magic Flutes because Eva Ibbotson is such a good writer that her characters break the bonds of the romantic novel. True, the hero, Guy, is an abandoned orphan who makes his way to the top of the business world and whose "strange green eyes," when he's happy, have "a gleam of the purest, the most celestial blue." His fortune has enabled him to win the beauty who rejected him years before and to buy her a German castle where "The Duchess wore a black lace dress to the hem of which adhered a number of cobwebs and what appeared to be a piece of cheese."

There is also the Princess of Pfaffenstein, aka Putzerl or Tessa, an ardent republican who works as a slavey for a Viennese Opera . Her endlessly rejected suitor, Maxi, is "perfectly aware of the advantage of marrying Putzerl. When you took Putzerl out onto the lake, there was no need to take a call duck. She could imitate, like no one he had ever met, the cry of a mallard ready to mate." Maxi decides to insure success by bringing his five dogs along on his next proposal. "You know how she is about dogs," he reassures his mother. "Four o'clock, therefore, saw Maxi rowing strongly towards the centre of the lake, the Princess of Pfaffenstein captive in the stern. Not only did he have Tessa, and in a most romantic setting . . . but he had the dogs. To get five dogs into a small rowing boat is not easy, but he had managed it and though the animals were a little bit on edge owing to the unfortunate proximity of a brace of mallard and a swan, they were behaving well." Thus begins one of the funnier scenes in a thoroughly charming love story set in turn-of-the-century Vienna, which matches an obsessed and eccentric opera company and a group of fading aristocrats against representatives of England's proper and rigid middle class. DREAM OF ORCHIDS

By Phyllis A. Whitney. Doubleday. 303 pp. $15.95

IN Dream of Orchids we are in the hands of Phyllis A. Whitney, whose masterful mixture of one part mystery to one part romance has produced a formula which has served her well for 30 books. With the plot bouncing along at such a happy pace, it would be quibbling to demand depth, though we do drop down full fathom five in search of buried treasure. It is modern day Key West, and Laurel York has come to meet the father she hasn't seen since she was three. The author greases our slide into fantasy with a bit of information about orchids -- ". . . you can grow new types quite easily and have something original and different. These are cattleyas here -- there are loads of species in that family" -- and more about Key West -- "Some people say it was given the obvious name of Cayoste. But others claim that it's a corruption of Cayo Hueso, for 'Bone Island' -- because of the Indian bones found here in early days" -- but mostly we are drawn into the mysterious death of the stepmother, the strange behavior of Clifton York's secretary, the odd way the greenhouse door jammed shut and, oh love, sweet love, will Girl get Boy? THE STATE OF STONY LONESOME

By Jessamyn West. Harcourt Brace Jovanovich. 184 pp. $12.95

THE CONVERSATION of two people remembering, if the memory is enjoyable to both, rocks on like music or lovemaking," writes Jessamyn West in The State of Stony Lonesome, a last and lovely novel from an author who died last year.

Ginevra Chalmers is 4 when she falls in love with her uncle Zen. "For a little girl, an uncle is so much more of a man than a father . . . Are all fathers, if well tamed, nothing more than awkward mothers?"

Zen is separated from the woman he loves and "dusted with love germs like pollen. Zen had not only love germs, but also a fund of physical tenderness that he needed to expend -- but which not everyone wanted. He couldn't be fondling and nuzzling strangers; he couldn't blow gently into his father's ear; nor nibble the points of his mother's fingers. That left me."

Ginevra and Zen came together again in Valencia, California. It is 1917. She is 12, still "the little sweetheart" whom her glamorous uncle calls "Aunt Jetty . . . because you are a born aunt." Indeed she is, worrying that her father has fallen in love with another woman, that her little brother will go to the devil, so that "He almost never started anything that was fun without having me stop him because it was my duty." Against the weight of a worried youth is the lightness of her love for Zen and his for her.

He teaches her to be a woman and she, in her turn, teaches him when it is time to let her go. With child abusers leaping from every front page, it is nice to have a novel which reminds us that the loe of an older man -- even an uncle -- can help a girl grow up in the happiest possible way.