Don&rsquot be put off by the silly title. Mad About the Mekong (Harper Collins Rs 1,200) by John Keay is a really good book. On the surface it&rsquos the story of the 1867 French expedition to chart the Mekong river. This is a remarkable enough tale in itself&mdashthe now-forgotten team travelled further than the length of Africa and plotted over half the course of what is still one of the least tamed of the world&rsquos great rivers. But what really concerns veteran author John Keay is the expedition&rsquos consequences&mdasheffectively, the delineation of modern Southeast Asia. Had it not been for the thrusting ambition of the expedition&rsquos diminutive deputy leader, Francis Garnier, French involvement in Indochina might have taken a very different course. Thailand would be a different shape, and Cambodia and Laos might not even exist. As a tale of colonial delusion, greed and overreach, it&rsquos hard to beat. It&rsquos also a page-turning yarn of courage and determination, as well as a tribute to an astounding waterway, the tenth longest in the world. Keay interweaves the narrative of the expedition with evocative descriptions of the modern river, which in some respects has barely changed since 1867. Essential reading.