Water has always played a key role in human society. But could it have been the major environmental pressure that drove human evolution? Dr Alec Whickham thinks so, and when he finds the remains of a human ancestor on the shores of Lake Turkana in Kenya it's a dream come true. But not everyone shares his excitement at the find and soon a murder mystery overtakes the archaeology team's investigations. Now the team and the police have a more immediate puzzle to solve, and they need to do it quickly, before someone else dies. Academic rivalry is a powerful motivator, but could it really lead...