Over 5 kilometres long and 100 metres high, Iguau is the greatest waterfall in the world. Five times the size of Niagara, these awesome waterfalls are also home to one of the richest habitats on Earth: 2000 species of plants, 450 species of birds, 50 different mammals and more reptiles and insects than anyone has been able to count. This stunning film charts the dramatic daily lives of the animals and follows the rangers who risk their lives to guard them.