One by One - Season 3 (1987)

Donald and Paddy escort an orang-utan to a zoo, which later turns into a raging menace. Meanwhile a young eland with a tooth abscess attacks and kills it's keeper, and Donald comes under pressure from the press to put it down. Elsewhere a blind lady donates a mynah bird to the Bellington Zoo, where it is stolen by an underpriviledged boy from a nearby school.

A number of animals are killed at the Bellington Zoo and suspicions point to a keeper being responsible, it later transpires to be the work of a suspended prison officer who once worked at the zoo. Paddy is offered the post of head keeper at the Bellington and Liz masterminds an education centre at the zoo. Meanwhile Donald fights tooth and nail to prevent Challon using dubious methods to make money using the dolphins at Manford Safari Park.

Teddy Haslam accidentally shoots one of his hawks, while it is being stolen and takes it to Donald to save it, unfortunately Donald is not there and Ethel lends a hand, until Donald arrives. The education centre opens. A thief in the zoo turns out to be a young boy stealing money from the zoo pools and a pair of squirrels! Donald is called to see a miniature horse which has become the companion of a Llama, which unfortunately dies. Meanwhile at Manford Safari Park the tigers come down with a mysterious ailment which 'drowns' them. and needs all Donald's ingenuity to sort out. Which result in Donald and Challon being hunted through the enclosure by the big cats.

Whilst walking her dog across some wasteland, a young girl finds an abandoned orang-utan, which later is diagnosed as having hepatitis. Elsewhere there is an egg bound emu, escaped onagers and a heated exchange between a disreputable pet shop owner who sold the orang, and an angry Donald.

Donald is offered a job with animal entrepreneur Ben Friedhoffer. Meanwhile the Bellington Zoo is offered 3 black Panthers for a very low amount which makes Donald suspicious.

Liz is inadvertently poisoned by a number of poison arrow tree frogs that have been sent to the zoo instead of normal tree frogs. Paddy is devastated that he didn't check them first. Donald is called out what appears to be a Coypu at some local caves but instead turns out to be an Alligator.

On the eve of Ethe's wedding to Teddy, Donald is called to Madrid Zoo, where Shao-Shao the Giant Panda is showing signs of going into labour. A tearful Ethel asks Paddy to take his place in giving her away. After the baby panda is born he flies home to witness the marriage, to the delight of Ethel.