A Week In Books: The book that really sheds light on Clinton's presidency.

Next week sees a rare London appearance by the woman responsible for nurturing a much-loved spellbinder. He may often misbehave, and has trouble growing up, but this cheeky wizard still works his magic for millions of fans. Yes, Hillary Clinton arrives in Britain on Thursday to sell her memoirs. I had imagined, pre-publication, that readers would have swallowed their fill of Hill, Bill and the ex-president's misadventures. Evidently not.

In the age of celebrity, personality becomes the vehicle that carries political ideas into books. Many purchasers who dive into Living History for its marital melodrama will stick around for the New York politician's reflections on peace and justice. Hillary the media star will clear a space where Senator Clinton the strategic thinker can perform.

For better or worse, this is how political publishing works these days. To compete with the din of fame, other writers - especially from the radical side of the tracks - have to turn up the volume. That means, increasingly, the genre of polemic: sometimes a blessing, often a curse, invariably hard to do well. Pioneers such as Michael Moore and John Pilger have bred a tribe of dull ranters. Some of them have perfected the art of discussing geopolitics in the aggrieved whine of Harry Enfield's Kevin the Teenager.

Grave issues of war and peace, hunger and plenty, matter far too much for this kind of peevish attitudinising. For that reason, a truly grown-up indictment of Western - in this case, American - global policy deserves the warmest welcome. Samantha Power's book A Problem from Hell: America and the age of genocide (Flamingo, £9.99) reaches Britain after winning this year's Pulitzer for non-fiction. It has also harvested plaudits from admirers who range from Michael Ignatieff to Senator George Mitchell.

Powers delivers a hugely erudite and eloquent account of American indifference to, or complicity in, modern genocide - from the Ottoman slaughter of Armenians and Hitler's Holocaust to the killing-grounds of Cambodia, Iraq, Bosnia and Rwanda. She excels, above all, at portraits of the brave and often lonely campaigners who gave a voice to victims, from the Polish-born anti-Nazi lawyer Raphael Lemkin - who crafted the legal concept of "genocide" - to Romeo Dallaire, the French-Canadian UN peacekeeper who strove to halt the slide towards massacre in Rwanda.

For the Pilger camp, this may sound deeply suspicious - too much like an apologia for liberal imperialism and "humanitarian" warfare. Not at all: Power never advocates invasion after invasion, bombing after bombing, as a just way to safeguard human rights. Rather, she counts the bloody cost of a century of American disdain for active diplomacy and multilateral institutions. As she puts it, "The US should not frame its policy options in terms of doing nothing or unilaterally sending in the marines."

Uniting scholarly depth with humane detail, A Problem from Hell proves that the literature of politics and recent history can steer a path between the sterile extremes of gossip and invective. It also, incidentally, leaves Senator Clinton's husband looking more weasel than wizard, when Power investigates the murder of 7,000-plus Muslims by Bosnian Serb forces in July 1995. The touchy-feely president emerges here as a cynical, reactive opportunist, "more moved by the damage the fall of Srebrenica was doing to his presidency than by its effect on the lives of defenceless Muslims". There are some stains on a career record that no visit to a dry-cleaner will ever remove.