ZOYA; By Danielle Steel; Delacorte Press; $19.95; 446 pages.Danielle Steel has become a prude.

The author of some satisfyingly steamy books years ago apparently has decided to write "real" literature, and thus has abandoned her fans who seek lust between the pages.

Don't misunderstand me. I believe there is room for any and all kinds of books in this world. I also believe that no one kind of literature, like no one kind of music, is inherently superior or inferior to any other kind. Thus I believe that the trashy novel is as acceptable a genre as historical novels.

But Danielle Steel had decided to change horses in mid-stream. Just as one expects certain things from books written by Gore Vidal, James Clavell and Jackie Collins, one also expects a certain amount of sex (with redeeming social value, of course) in her books.

So I am warning you. There is no sex in Danielle Steel's latest book, "Zoya." I am aware that this book is No. 1 on the best-seller list, and I fear that Ms. Steel's fans expected something different when they bought the book.

Worse than the lack of titillation, however, is the book's relentlessly tragic tone. "Zoya" was a total bummer for me. Tragedy after tragedy befalls the title character and I, for one, find real life tragic enough without having to face it in books.

The book is very well written and a quick read. I know next to nothing about the Russian Revolution, and normally I hate period pieces, but this had a certain charm and showed how both sides lose in any uprising. I am sure readers who are into history-from-one-person's-view books will love it.

But I, like many people, read to escape real life. I want to laugh, or be fascinated with lifestyles I'll never see up close, and in general escape to a more pleasant place for a few hours. I don't want books that make me sad - I need only scan the newspaper for that.