Keeper Mike is on babysitting duty for the park's latest arrival, a baby woolly monkey, and nursery chimp Bryan falls in love - with his own reflection. Meanwhile, Alison and Jeremy are on a mission to rescue capuchin monkeys from Spain.
Staff are at a loss to know what is wrong with Trudy the chimp, and one of two capuchin monkeys brought back from Spain by Alison and Jeremy makes a bid for freedom.
Alison and Jeremy rescue a squirrel monkey called Samantha from a derelict farm, a young chimp tries to settle in a new set, and the bachelor chimps show off their sporting prowess.
Disaster strikes at the orang-utan nursery when builders try to fit the new windows, baby woolly monkey Diego meets one of his family for the first time, and Samantha the squirrel monkey gets the all-clear from the park's vet.
The chimps make snowballs as winter grips the park, and Jeremy keeps an all-night vigil as the condition of Charlie the chimp takes a turn for the worse.
Alison Cronin visits Dao Tien, Monkey World's sister centre in Vietnam, which was founded in 2008, and has since become the site of a pioneering rescue and rehabilitation mission for golden-cheeked gibbons. Here, the team faces trouble during an attempt to save a rare silver langur monkey, and director Marina asks human doctors to perform ground-breaking eye surgery on a gibbon.
A mysterious accident puts a baby monkey's life in danger, while snowfall keeps most of the chimps inside, where they tuck into jacket potatoes to help keep the winter chills away.
Alison goes to great lengths when Trudy falls victim to a mysterious condition. Marcel the marmoset demonstrates small monkeys can be as clever as the larger apes, and baby woolly monkey Diego is allowed to join the adults.
Spanish capuchin monkeys Babe and Amy try to make new friends, while two others receive a lesson on wild behaviour. Elsewhere, Alison Cronin heads for Belfast to pick up a ring-tailed lemur that took over a family home.
Golden-cheeked gibbon Peanut presents her newborn, Jeremy confirms orang-utan Hsiao-Quai is pregnant - and the team suspects woolly monkey Yarima is, too.
Chimps Busta and Mickey have their teeth checked on dentist day at the sanctuary, and Spanish capuchins Babe and Amy take on dominant female Debbie.
Pip the chimp undergoes a tricky operation, Kaiyah the ring-tailed lemur receives a family visit - and the staff create a frenzy by treating the chimpanzees to ice lollies.
The rehabilitation of new arrivals at the capuchin house is going well, but the keepers struggle to persuade the former lab monkeys to climb as they would in the wild. Plus, chimp Ben joins two old friends in the park's bachelor group.
A police raid on a farm uncovers two rare chimps from Colombia that desperately need a new home, and Ben the chimp prepares to meet Butch, an important figure in the centre's bachelor enclosure.
Kaiyah the ring-tailed lemur struggles to adapt to her new enclosure after spending her early years cooped up as a pet. The keepers think they have solved the mystery of Peanut's baby and Ben the chimp finally settles in with his new group.
The chimps enjoy a party with buckets, jelly and soap suds provided, and Peanut requires an operation on her torn lip.
Vet Mike tailors a designer jacket for capuchin Bruce, baby Tia-Nang tries to prove to her mother she is a grown-up, and Marina from the sister sanctuary in Vietnam checks on the progress of the golden-cheeked gibbons.
Alison Cronin goes undercover to save a chimp forced to work as a photographer's prop in Turkey, and turns to her Dorset MP for help.
The world's oldest woolly monkey Xuzie is diagnosed with depression, while concerns remain over Trudy the chimp. At the orang-utan enclosure, there is great excitement over Hsiao-Quai's early delivery.
Staff grow anxious when orang-utan Hsiao-quai refuses to bring her newborn baby indoors during a storm. Ailing chimp Trudy's condition starts to improve when she begins a strict new diet and 38-year-old Xuzie, the world's oldest woolly monkey, gets a treat of giant locusts to help build up her strength.