The hippopotamus has long been an enigma: an aquatic mammal that cannot swim, a vegetarian that is also the most dangerous animal in Africa. All hippos are utterly dependent on water, but in Botswana, hippos face an unparalleled challenge as deep floodwaters dry to dust in a matter of months. The documentary goes beneath the surface to show how hippos protect their families and face their enemies, revealing an animal that is highly sensitive and surprisingly...