Mantas eat plankton, not fish. So why would oceanic manta rays, among the largest of the species, make an annual pilgrimage from the waters of Mozambique all the way to the coast of South Africa to attend the sardine run, the world's largest migration of marine animals? Follow dedicated manta researchers as they work tirelessly to discover the secrets of one of the ocean's most mysterious and majestic dwellers. They might even discover new species along the way.