Nigel Marven is on a mission. He wants to find out the truth behind the legend of the Piranha. In this brilliant programme, Nigel travels through the waterways of South America immersing himself in the Pirahna's world. From breeding to feeding, birth to death, all aspects of Piranhas' natural history are uncovered with spectacular wildlife images. After swimming near a Piranha nest, hand-feeding a shoal in a feeding frenzy and studying Giant Otters' feeding habits, he realises that Piranhas are much maligned and play a vital role in maintaining the health of the waters of South America. This fresh and exciting documentary is a must-see for all animal lovers.