In 2007, scientists from the Wildlife Conservation Society discovered there were an estimated 125,000 western lowland gorillas living in the remote forests of northern Congo. This find offers another chance to protect this endangered great ape and a first look at some unprecedented behaviour - including a knack for using tools. Now primatologist and National Geographic explorer Mireya Mayor ventures into the heart of the jungle to explore the great apes' secret world. She gets a rare and intimate look into the family life of one gorilla group and witnesses individuals performing feats unexpected in the wild. Spectacularly photographed and featuring new scientific insight, Mystery Gorilla presents startlingly familiar animals like you've never seen them before.

• 1 disc; 52 minutes
• © 2010