In this documentary we meet the only 'talking' gorilla in the world, Koko. Well, by talking we mean sign language but it truly is impressive to watch this animal in action. Koko understands spoken English and can use over a thousand signs to communicate her thoughts. Project Koko began as a PhD project by animal psychologist Penny Patterson back in the seventies, but an intense bond formed between the pair, and they have now been together for over 40 years. The programme shows footage of the most dramatic moments of Koko's unique life with Penny, from the battle to prevent the gorilla being taken back to the zoo in which she was born, to a clash with academic critics. Robin Williams also famously met the gorilla back in 2001 and the pair formed a bond, and Koko is said to have expressed grief on hearing about his death in 2014.