BOOK REVIEW : From the Convent to the Unconventional : DEVILS, FOR A CHANGE <i> by Wendy Perriam</i> St. Martin’s Press $19.95, 469 pages

Some books you like or dislike unreservedly; some, you like despite their weaknesses, or dislike despite their strengths. A few, however, have the power to make you like them, not merely in spite of their flaws but along with, even because of them. Such a book is Wendy Perriam’s latest novel, “Devils, for a Change.”

The story is of Hilary Reed, the former Sister Mary Hilary, an English contemplative nun in one of the strictest orders in Europe, who, as the book opens, quite suddenly leaves her order and makes her way to London. Over the course of a year, she meets a variety of people, has adventures, romances, disillusionments and crises of faith, and emerges at the end changed, strengthened, still spiritual but also occasionally ready to be a “devil, for a change.”

The triumph of the book is in the character of Hilary. Perriam has a rare ability to get under the skin of her main character--a bit too far under, in fact, in the case of the supremely irritating, whining protagonist of her previous “Under Purple.” Hilary, though, is another kettle of fish. She is intelligent, earnest and a little simple. She is lacking somewhat in self-confidence, and somewhat more in humor; she makes occasional faulty judgments, and becomes, often, extremely confused; she desperately wants to do the moral thing. You recognize her immediately and are rooting for her all the way.

It is through her mercy, too, that you get a quite wonderfully vivid, yet impartial, view of convent life. Perriam knows her convents through and through, and--more unusual--she has remained able to view them without apparent prejudice either for or against. Thus we are shown without prurience the chosen rigors of the life--the bare feet on cold mornings, the active seeking of “penance,” the constant quest to humble the body by denial of pleasures. We are shown, too, without sentiment, that distinctive, childlike charm peculiar to many nuns: the delight in luxuries smaller than most of us would notice, the sheer, cloistered innocence of them.

Set against the convent is the description of modern London, beginning with a horribly accurate six-page picture of the underground at rush hour and continuing by turns terrible, poignant and comical; Hilary, Candide-like, encounters every aspect of the modern world, from post-punk haircuts to lessons in the Alexander technique, from tampons to charismatic priests.

Both environments are convincingly portrayed; each bounces off the other in a way that can only intensify both.

Where the book falters is in the many other characters that Hilary meets in her quest for self-fulfillment. Each appears to possess just one outstanding characteristic. Thus, you have, appearing in turn, the Earthy Working Woman, the Problem Child, the Feminist, the Ardent Suitor, etc. The speech habits of each can only be called curious, not so in conversations with Hilary as delivering to her, sometimes within minutes of introduction, miniature disquisitions, stating precisely what they feel about a given situation, offering a couple of alternative reasons why they might feel it, and quite often backing it all up with some statistics they just happen to have read in a magazine.

How many, for instance, 17-year-old beauticians--or, indeed, any 17-year-old anythings--do you know who talk like this:

“Nor am I (married). But it doesn’t stop me having sex. Don’t get me wrong, Hilary, I wouldn’t sleep around. It’s far too dangerous nowadays, apart from being cheap. But if I meet a bloke I like--and trust--then I’ll go to bed with him. It’s part of being human, part of living. . . . All my crowd feel much the same. . . .” And on, and on and on.

After a couple of hundred pages of this, you are left with two choices: tossing the book aside wearily, or deciding to adapt to its rhythm. With “Devils,” you opt for the latter, because it is, on the whole, a very good book--in both the moral and the literary sense--and because Hilary is so very real, so very admirable, and because you care so very much that she find the right answers.

After a bit, you find yourself actually enjoying the dialogue, the way you do the quirks of an eccentric but well-loved friend.

And as Hilary herself finds in the course of the book, you really shouldn’t expect perfection.

Next: Elaine Kendall reviews “Jakob the Liar” by Jurek Becker (Schocken Books).