The jungles of Borneo can bring adventurers to their knees--and elevate adventurous writers to admirable heights, as evidenced by Eric Hansen's Stranger in the Forest (1987) and, now, by free-lance writer Johnston's smart, passionate account of rafting down the island's treacherous Boh River. When Johnston arrived in Jakarta on the first leg of her journey to the Boh, she learned that her luggage had remained in L.A.--a portent of miserable weeks to come. Ill-equipped but still game, she joined her companions, who included--in addition to three guides paid for by Sobek, the travel company sponsoring Johnston as the trip's writer--two high-fashion models, a wealthy Italian, a Florida couple, a Chicago lawyer, and a pair of young Australians. Each flares to life on Johnston's crisp pages, but none more so than the author herself. For as much as an exciting jungle journey, Johnston's trip reveals itself as an odyssey of self-discovery during which she, the only group member over 40, enters menopause. And with the hot flashes that strike in the middle of the steaming nights comes knowledge of a border crossed: ``Yesterday, I had been young; today I was middle-aged.'' Always proud of her physical prowess, Johnston now must reorient herself as a woman whose primary challenges will be emotional and mental, not physical. And the trip itself develops into just such a challenge as the author and her companions struggle through Job-like trials generated by bees, leeches, ants, rapids, waterfalls, floods, rancid food, open sores, foot rot, moldy clothes, and, above all, the unrelenting wet heat that turns the jungle into a sauna from hell: ``I was surprised all over again at how spongy and rotten everything was. The entire forest floor was being devoured by ravenous microorganisms....'' A powerful adventure of the heart as well as the body: not to be missed.