S1, E3: Botswana is home to more African elephants than anywhere else in the world. Every year, thousands of elephants trek over 7,000 miles in search of food and life-giving water. The desert is a hostile place, especially as the dry season takes hold, so the elephants must use their strength and wit to survive. Along the way, they are shadowed by some of the most ruthless predators on earth – lions.