Gordon Buchanan realises a lifelong dream by gaining the trust of a family of rare Grauer's gorillas, the largest primates on Earth. In the dangerous forests of the Democratic Republic of Congo, he meets thefearsome leader of his gorilla family, Chimanuka, and two baby gorillas, one a lonely orphan. As Gordon gains the trust of these mysterious, seldom-seen gorillas, he discovers their incredible compassion and gets caught up in a battle between giant rival silverbacks for control of the family.