The Lost River explores the geography, history, and mythology, of the Sarasvati river, drawing from various sources like folklore, the Vedas, archaeology, local practices, history, geology, and meteorology. The book explains that the river, its very existence, and its course have been discussed and speculated over for years. The magnificence of the Sarasvati has been detailed in scriptures like the Rig Veda. Historians and archaeologists could not understand how it mysteriously ceased to exist. Some of the even deem the river a myth. This book attempts the deduce facts from fable and makes a strong case for the existence of the river. It goes over the upheavals that the Indian subcontinent went through thousands of years ago, explaining the dry weather, erosion, and tectonic events that changed the terrain, altered river courses, and may have made the Sarasvati disappear. The book then chronicles explorations into the river started, which began around the early nineteenth century, when it was rediscovered by British officials doing topographic explorations. The book also explains the culture around that time, shedding light on the Indus valley civilisation and the rich and flourishing culture of Harappa. The book goes on the show the results of explorations into the river’s origins and course using modern technology like satellite imagery and isotope analysis. The author has also used his proof of the existence of the river to bolster his theory that Aryans were indigenous to India and not foreign invaders.