In the third episode, Will Smith crosses the Serengeti to catch one of the greatest events of nature. "An image, one and a half million wildebeests on the plains of Africa in the most dramatic migration on Earth, has stayed with me since around thirty years ago I picked up a National Geographic Magazine and saw it. And finally, I'm here to see it."

As summer spreads across our planet, honey bees toil, snow geese breed, tadpoles awaken and lions stalk wildebeest in search of lush grass.
Our planet is solar-powered. But due to the Earth's tilt, it doesn't strike its surface evenly. This solar energy arrives in varying amounts at different times of the year. The huge increase that comes with summer also triggers countless migrations.

The fourth episode of the series takes you on an epic journey through time, beginning 252 million years ago, in a world devastated by the greatest mass extinction in history. Discover how, from the ashes of this cataclysm, fungi become the dominant form of life in an almost apocalyptic landscape. Witness the astonishing story of survival and adaptation of the Lystrosaurus, curious ancestors of mammals, who emerge as the unlikely heirs of the Earth and transform into the dominant creatures, only to be eventually dethroned by new giant predators like the Erythrosuchus. The documentary culminates with the impressive era of dinosaurs and how they adapted to a constantly changing world, and the reigns of the plesiosaurs and pterosaurs, rulers of the oceans and the air. Finally, learn how these titans gave way to modern reptiles and current birds, leaving a legacy that endures to this day.
This documentary is a window into the fascinating evolutionary history of our planet, showing the resilience and diversity of life through the ages. Prepare to be amazed, informed, and deeply moved by this spectacular chronicle of life on our planet.

Some animals give their young the best start in life by making truly astonishing journeys. And it's not only where they go that's important but when. Left to fend for themselves until they find their footing, baby sea turtles, elephant seal pups, pumas and crabs bravely trek towards adolescence.