The migration reaches Kenya's Masai Mara where, for the calf, the river presents his greatest challenge yet. Croccam, Skullcam, Tortoisecam and Hippocam are just some of the spycams following the calf as he crosses the raging torrents. They film, up close and personal, as crocodiles pick-off stragglers, hippos become carnivorous and the river's sheer walls become death-traps.