One by One

Donald Turner arrives home in Rochdale fresh from graduating as a fully qualified Veterinary Surgeon, and takes up a position with grumpy older vet Maurice Webb. He is horrified to learn that the Great Northern Zoo is a part of the practice, especially when he is called out on Maurice's day off to treat a chimpanzee who has had a thumb bitten off. The vet is needed so that they can say they 'Called In The Experts'.

Donald and Maurice are called to the zoo when a female elephant is in extreme pain in her jaw, and is getting more and more debilitated and dangerous. Donald and Maurice discover that the elephant has severe arthritis and there just aren't the drugs to deal with it, and are forced to euthanase her. Donald is left in a black mood as he doesn't consider that he can help any of the animals at the zoo, with his limited knowledge.

Mr. Webb is very displeased when the newspapers learn about the elephant's death, but Donald decides to dig in and learn all he can when Rajah the tiger is poisoned by a disgruntled ex-keeper.

Donald goes on an interview for another job, and watches as Jenny mounts a newspaper campaign to keep the zoo open.

Donald decides to take the new job, but has some misgivings about leaving the zoo animals in Webb's care and Jenny is offered a position with a London newspaper.

Donald is called in to inspect the animals at a local circus and teaches an old seal trainer some new tricks, and he helps Paddy Reilly find some missing monkeys at the zoo.

Donald is now well-known as a zoo vet, and is travelling the country dealing with circus animals, but still finds time to deal with the Great Northern Zoo's animals. The Northern Zoo itself is having a rough patch with Paddy acting as senior keeper and manager, and doesn'thold any illusions as to what is going to happen to the zoo. Maurice is annoyed about the amount of time Donald is away from the practice, and is even more annoyed when Donald informs him of a proposed safari park he will be involved with. Things finally come to a head when an elephant escapes from Ben Bishop's circus and injures a man, and forces Donald to split up the partnership.

Donald encounters a hostile lion trainer at the proposed safari park and is called in to treat three tiny alligators at a local night club.

Donald investigates the strange behavior and requests of an Italian couple with a trained dog act who are waiting out their quarantine at the zoo, and Ethel formally joins Donald at the safari park.

Donald helps prepare a dog for burial and meets an American dolphin expert.

Donald and Paddy battle a callous administrator as they struggle without much success to place all the zoo animals before the closing day.

Donald solves the riddle of vandalism in the village and an attack on a local vagrant, and provides a home for a laboratory baboon due to be put down.

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.