BY VALERIE SAYERSA CHANGE IN ALTITUDE. Anita Shreve. Little, Brown. 307 pages. $26.99.
Anita Shreve is a bestselling novelist in large part because of the economical way she builds suspense. In the first line of her new book, a young white doctor who has arrived in Nairobi to conduct research, announces, ``We're climbing Mount Kenya.'' In those four words to his wife, he suggests the story's central questions: Why is Patrick telling Margaret, with her scant climbing experience, rather than asking her? Can the young American couple rise to the physical and psychological challenge? And what will this climb allow them to discover about Kenya and about themselves?
The novel, set in the 1970s, is told from Margaret's angle and, because she is a photographer, that perspective is often visual and sharply focused. She's especially sensitive to those who claim authority, and that includes all five of her climbing partners: She and Patrick, accompanied by a guide and porters, take on Mount Kenya with two European couples well accustomed to wielding the authority of post-Mau Mau white colonials. Patrick and Margaret's landlord, Arthur, is the one who has suggested the climb, and Margaret has certainly noticed the proprietary attention he pays her. Arthur's athletic wife, Diana, has noticed, too.
Shreve's prose is workaday here, and the dialogue is occasionally stiff, but she knows how to keep a reader engaged. Sometimes, Margaret's interior monologue does a good job of explaining a bit of action: ``After she had stumbled a couple of times, she noticed that the cook, whose name she didn't know (whose name she didn't know!), stood near her in case she fell badly.'' More often, however, Margaret's thoughts are separated from the action and tend to state her dilemmas baldly. In the middle of the night, she wakes in their mountain shelter to find rats crawling over her, and allows Arthur to comfort her by taking her hand. The passage describing the morning after seems designed to reassure those readers who are a little slow on the uptake: ``She wondered who else had seen her hand in Arthur's, and if that explained the angry voices outside.''