Mueller's gibbons Adidas and Dalumie head for the treetops for the first time, while Peanut, Pung-Yo and Tien move into the enclosure next door. Plus, a specialist doctor is called in when Freddy's bowel complaint fails to improve.
Chimp Ben's foot infection has led to the amputation of one of his toes. Just as he's improving, Honey, one of the chimps in Hananya's house, is struck down by the mysterious bacterial infection - and it is serious.
Chimp Ben's mysterious infection has spread to some of the others in his group, and it's a race against time to diagnose and treat it effectively. Meanwhile, the orang-utans are watching their weight, but are not so keen to get onto the scales.
Chimp Ben has a nasty infection and animal director Jeremy is worried it may lead to him losing his foot. Elsewhere, golden-cheeked gibbon Tien has undergone a transformation, and keeper Holly checks up on Xuzy.
There is a scuffle between the female capuchins, Tia needs surgery, and orang-utan Amy is heavily pregnant - and very grumpy. Meanwhile, there is something new in the play area of the chimp nursery, and Alison has her last visit with Paulo.
Eighty-eight capuchin monkeys rescued from a research laboratory in Chile wake up to their first morning at Monkey World. Rodders has a run-in with a sticky melon, and Seamus the chimp comes face to face with alpha male Butch.
Aris is still doing poorly after his operation, the baby woolly monkey finally gets a name, and the alpha male chimps exert their authority, but there might be a coup brewing.
The 88 Chilean capuchins finally arrive in the UK, but there is bad news in the orangutan house - something has gone seriously wrong for Aris since his knee operation.
The teams travels to Chile, where they have joined forces with the military to fly 88 Capuchin monkeys to Monkey World. It will be the park's biggest and most challenging rescue ever.
Orang-utan Aris needs surgery as his knee injury is worse than expected, chimp Patricia finally relaxes in the company of alpha male, Hananya, and chimpanzee Seamus is in for a shock when he meets big male, Paco.
Seamus moves from the chimp nursery into the bachelor pad. Toddler orangutan Aris is in recovery when one of his new housemates decides to pick a fight with him.
It is a vet day at the park, and John Lewis checks up on the leg that chimp Jimmy nearly lost. Meanwhile, baby chimpanzee Rodders must have a tooth removed after sustaining an injury during a play session.
Seamus's brief period of calm comes to an abrupt end, chimp Susie takes her new baby outside for the first time, and the team encounters problems with the travel arrangements for the Chile trip.
The new baby woolly monkey meets its own kind for the very first time, orang-utan Aris graduates from the nursery and meets Gordon, and there is a surprise in the chimp nursery as the cheeky Seamus seems to have learned to control his wild side.
It is a day of tense introductions for the chimpanzees and the gibbons, and the team begins work on its biggest mission to date - the rescue of almost 100 primates from a Chilean research laboratory.
Construction begins on the new gibbon rescue center in Vietnam as the first primates are already arriving to begin their rehabilitation. Members of the bachelor chimp group fall out once again.
Monkey World is embarking on a new project in Vietnam, its first foreign sanctuary for endangered primates. A new gibbon rescue centre is being built to protect these rare animals for the future.
Things are looking up when chimp toddler Bryan makes his peace with bad boy of the group, Seamus. However, it's not long before they fall out again.
Jim and Alison are in Mexico to find Bryan, a young male chimp. Exploited as a beach photographer's prop, he is looking for a new home among his own kind.
It's time for baby woolly monkey Julio to leave his life living with humans, and there's a shocking exit from the park for a capuchin monkey family when, 18 months after their rescue, a court order means they have to leave.