Patrick Stewart narrates a landmark three-part series on the world's last mountain gorillas. The largest gorilla family in the world is starting the perilous journey down to feed on the fresh shoots of bamboo. They run the risk of being caught in illegal snares and Cantsbee, the dominant silverback, will have his work cut out keeping them all safe, especially those closest to him. Meanwhile on the other side of the Rwandan volcanoes a young gorilla has been deserted by her mother. She turns to her silverback father for guidance and protection, but is he up to the job? In Uganda, Marembo the teenage silverback has come of age. He has lived 15 years under the watchful eye of dominant silverback Rukina but now feels it is time to make the break on his own.