Each year more than one million wildebeest and a quarter of a million zebra and gazelle migrate on Tanzania's Serengeti Plains, to graze on the green, short grass plains - one of the most spectacular events in the natural world. But what happens to the predators they leave behind? Lions are territorial animals, hunting only the animals that come into their territory. As the herds move north following the rains and fresh pastures, within a few months the short grass plains are reduced to dry wastelands and not a single herd animal is left, leaving the lions behind to tough it out until their return. Over an unprecedented year of filming, Nature's Great Events highlights the desperate plight of a single pride of lions - a story not often told. Not long after the herds' departure, the lions and their seven cubs are already suffering. Unable to follow the wildebeest, the female lions struggle to find enough food for their hungry offspring. Added to the struggle, a fire rages through the lions' territory destroying the cover they so desperately need in order to ambush the few prey animals that remain. Will the pride survive until the herds return?