The Chitwan National Park stretches along the base of the Himalayas. This vast expanse of wetland is home to the endangered Indian rhinoceros. Weighing up to 3 tons, these massive beasts look like they're wearing body armors. Because they spend most of their time hiding deep in the wetlands, sightings are rare. Recent studies, however, have revealed that at a specific time in the summer, they gather in great masses at a single large marsh. With the focus on a mother and her calf, this episode reveals amazing new truths about rhinoceroses, including the secret behind their mass gatherings.