David Attenborough narrates this documentary following young research student Anne Orlando as she sets out on an unforgettable adventure, hoping to solve the mysteries surrounding a herd of elephants that inhabit the desert south of the fabled city of Timbuktu. How do they survive the arid conditions? Why do they disappear for two months each year? And why do they make an annual journey across the desert?

Last year, while excavating a 5,000 year old temple buried by Egyptian sands, archaeologist Edda Bresciani unearthed a sacred chamber - with an unexpected secret.There in the center of the room, gleamed an iridescent pool of emerald water. And right next to it, in a small depression hewn into the floor - thirty perfectly preserved crocodile eggs. Nearby were mummified adults. "The temple was a nursery for sacred crocodiles," she says incredulously. "They emerged from the eggs, to be reared in the pool before being sacrificed and mummified. I'd found a temple to Sebek - the crocodileheaded deity." Despite their revered status in ancient Egypt, the crocodiles in the river Nile were all hunted out by the 1800s, and the Pharaoh's crocodiles were lost forever. Or so it was thought.Then there came mysterious sightings of crocodiles emerging from strange places in north Africa away from the Egyptian Nile. Are these the long lost ancestors of the Pharaoh's crocodiles - alive and well?