The female capuchins fight, Tia needs surgery, and orangutan Amy enters the late stages of pregnancy. Elsewhere, there is a new addition to the play area in the chimp nursery, and Alison visits Paulo - the baby woolly monkey she has successfully hand-reared - for the final time.

An infection threatens to sweep through the chimpanzees, prompting the keepers to begin urgent action to save their lives. Meanwhile, the overweight orang-utans continue with their diet and the lemurs are introduced to the stump-tailed macaques before they move in together.