Elephant specialist Martyn Colbeck tells the story of two baby elephants struggling to survive. Their first six months are critical in the starkly beautiful deserts of Namibia. This is the most endangered elephant population in the world - it was devastated by poaching in the 80s, so every new calf is vital. It's a boom year, but when rivers disappear underground, their survival depends on the females who lead their young from one remembered food source to the next.