An eye-opening exposÇ of the workings of the tobacco industry, based on the leaked internal documents of a leading cigarette company. The setup is that of a thriller: In the spring of 1994 an express-mail box filled with 4,000 pages of tobacco-company documents turns up on the doorstep of longtime industry critic Glantz (Medicine/Univ. of California, San Francisco); the return address read ``Mr. Butts,'' the name of the fast-talking cigarette from Doonesbury. Glantz assembles a team of medical doctors and policy analysts to comb through the papers, which he lodges in the special collections division of the university library so that Brown & Williamson, the tobacco company in question, cannot block public access to them. The documents are astonishing, describing research projects with codenames like ARIEL (which sought ways to boost the nicotine kick of a cigarette), giving a behind-the-scenes look at the company's maneuverings around various lawsuits and congressional inquiries, and showing beyond any doubt that B&W, at least, was well aware of the cancerous effects of smoking decades ago, although it continues to maintain that ``causation has not been proved'' and that nicotine is not addictive. (Smokers may also be interested to know of B&W's experiments with various additives, including benzo(a)pyrene, cocoa, and deer tongue, a plant substance known to cause liver damage in test animals.) The editors' commentary helps make sense of the often arcane papers, which are couched in the language of law, chemistry, and medicine; even with their help, however, this makes for tough slogging. ``Stall any disclosure by industry as long as possible,'' one B&W memo urges. Difficult as it is to work one's way through this book, the labor yields disclosures of the sort that doubtless makes for an industry insider's worst nightmare--revelations that will add new fuel to the widening debate about smoking.