James meets a pair of elderly twins. Oliver and Roland Strong, rabbit breeder and prize cabbage-grower respectively, have divided the cottage left to them by their mother and have not spoken to each other for 50 years. Now Oliver is convinced that Roland has poisoned one of his rabbits.

When James treats a sick cat, he finds himself in an awkward position with Mrs. Pumphrey and Mrs.Tibbett. These two formidable and mutually ferocious Darrowby matrons compete both in presents for the invalid and in hounding James for information of the patient's progress.

When Lady Hulton's cat falls ill, Siegfried embarks, with typical zeal, on updating the practice to cater for such refined clients. Lady Hulton, however, catches him out at every turn. James' problems lie with an affable but lazy farmer, Vernon Harker, whose plans to save himself from work even extend to marrying a tower of strength with a grown son to match.

Jenny Garston and David Rayner, individually charming farmer and horse-breeder, have been sworn enemies since their earliest school days. When a triple birthday is marred by tragedy it falls to Siegfried to negotiate with the stony-faced neighbors.

Life at the Yorkshire veterinary practice continues to challenge the partners, whether by neglected animals or tight-fisted farmers. There are domestic challenges for Tristan, however, when James and Helen play a practical joke with a "Welcome Home" card from an old female admirer. Life is never simple when true love or the demon drink rule Tristan's life, and he is soon in trouble with Siegfried. A new housekeeper, Mrs. Alton, has been recruited by Siegfried to keep a watchful eye on Tristan, who, dispatched to tie up the details of her employment, is delighted to discover that Mrs. Alton is a rather attractive young widow. But this is not the Mrs. Alton that Siegfried had in mind.

Planting a syringe full of anti-abortion vaccine into a farmer's backside creates something of a crisis for Tristan. Farmer Nat Briggs is convinced that his chances of starting a family have been ruined by Tristan's clumsiness, and he hangs threateningly around the Drovers waiting for a chance to confront Tristan. But it is Siegfried who gets a letter threatening court action. James, meanwhile, keeps Helen guessing about his mysterious visits to a local joiner, whose pet, Helen knows, died some time ago.

Tristan's heart is all a flutter because of the lovely Jane Mercer. When he discovers that she sings in the choral society, Tristan develops a fresh interest in matters musical. But strong-willed Jane takes a donkey's owner to task for neglecting the animal, much to the embarrassment of Tristan. Farmer Biggins, meanwhile, baffles all three partners with his strange behavior. A legendary non-payer of vets' bills, he finally meets his match when Granville Bennett - "the finest small animal practitioner in the north" attends his tom cat and manages to get Biggins to settle his outstanding account in full.

The mysterious Mrs. Donovan poses problems for all three partners. Siegfried rashly dismisses her as "a warm-hearted woman who loves animals" -- until she starts interfering with his patients. From sheep to piglets, a howling dog to a hibernating tortoise, there seems to be no limit to her homespun remedies. Tristan has big trouble on his hands when cadging college pal St. John turns up looking for a bed -- and a small loan. Can Tristan keep St. John's presence a secret from Siegfried and the fearsome Mrs. Alton? Lovely Rosemary Brocklehurst attracts the romantic attention of Tristan when she brings in Esmerelda, a tortoise, which won't come out of its shell. Perhaps Mrs. Donovan has the answer...