Tristan and Charlotte enjoy a romantic picnic at Beauvoir Manor, but they are aware that his leave is almost over meaning he will have to return to war soon. James checks in at Heston Grange and meets Richard's new farmhand, Butch Fielding. Richard admits he's had the new telephone off the hook because he keeps getting nuisance calls.

May 1945, and things look very different at Skeldale House as James is struggling with a wild and chaotic Siegfried. When Tristan returns from war and is shocked to see the shift in his brother, he and James decide to take action. But there's also some good news around the corner for everyone.

As Chamberlain heads to meet with Hitler in Munich, James prepares to face his parents and give them some difficult news. Meanwhile, James's agenda is derailed by an emergency with the Alderson's pregnant mare, Candy.

Helen is thrilled when Jenny gets exciting news and sets about getting her sister prepared for a big move, but soon realises neither of them are ready for it. Mrs Hall asks for time off for her granddaughter's birthday in Sunderland, and Siegfried starts to panic.

James and Helen spend their first Christmas together, but must agree on where to spend it. Despite all seeming idyllic, the vets are troubled as Tricki Woo is sick.

James is worried about the practice finances, but it falls on deaf ears when he tries to discuss the matter with Siegfried. Herriot decides to take on the role of attending vet at Hensfield dog track to earn extra money. Meanwhile, Tristan visits Mrs Ainsley, who has an aggressive parrot called George.

James' workload doubles when Siegfried takes ill during a harsh winter. Mrs Hall discovers it is James' birthday, and Tristan tries his best to cheer him up by arranging a double date. Season finale.

Mrs Hall's world is rocked by bad news. Meanwhile, Tristan is given a special wartime mission involving pigeons, and the house readies to celebrate Jimmy's birthday.

James is exhausted running between Heston and Skeldale, and to make matters worse, he's often finding himself on the wrong side of Richard Alderson, who is miffed about the muddy floor. Meanwhile, Mrs Hall and Herriot are curious about what Siegfried's been up to when James finds him wandering home after a night out.

James is trying to bury his pain over Helen and has invited his new girlfriend Connie to the annual Skeldale Christmas party. As the house fills with locals, James receives a call from a man who wants help with his dog who is giving birth.

It’s Christmas in Darrowby and everyone is trying to make the most of things while the world is at war. A young guest brings some wonder, mischief and cheer to Skeldale House while everyone waits for important news. When Mrs Pumphrey heralds the arrival of a kitten in need of extra care. Siegfried is asked to pay a visit to an injured River just before a big race.

Siegfried receives some difficult news and becomes even more irascible than usual. The perfect distraction comes along in the form of Major Sebright Saunders, who asks Siegfried to look at a difficult young racehorse called River.

Siegfried and Tristan are left in charge of Skeldale House, when Mrs Hall takes time off to meet up with an important person from her past. Siegfried immediately puts Tristan in charge of housekeeping duties and focuses on running the practice and educating a visiting work experience boy named Andrew Simmonds.

The war is getting closer, James is about to embark on a new journey. He desperately wants things in order and Carmody trained up to support Siegfried. But James is frustrated at Carmody’s inability to drive and he keeps missing opportunities to spend precious time with Helen.

Tristan sets about collecting debts owed to the surgery and takes a shine to Maggie, the new barmaid at The Drovers. Siegfried hopes to bag the job of Attending Vet at Darrowby Racecourse, by buttering up the head of the race course, General Ransom. When the favourite to win on the race day is diagnosed with a inoperable condition, James has his first painful experience.

It’s spring in 1938, and a trip back home to Glasgow presents James Herriot with a dilemma that will mean choosing between the people he loves when he is offered a position at his old mentor's forward-thinking practice.

With Tristan's encouragement, James asks Helen if she'd like to go to the local spring dance. But village resident Gerald's arrival with his injured dog, Rock, puts a spanner in the works. Meanwhile, Tristan worries that Siegfried is in danger of losing his edge.

The Skeldale House regulars think about what matters to them most when the radio reports that Britain is standing on the brink of war. As everyone processes the news, James discovers a case of TB at Heston Grange. Richard begs him not to report it or the farm will be shut down and he could lose his livelihood.

Helen feels redundant at Skeldale, and buried family secrets threaten to tear their relationship apart as Richard refuses to let her muck in on the farm. Helen notices that calf Smokey seems unwell and tries to help him, but it only makes things worse with her dad.

An emotional phone call with a very pregnant Helen makes James determined to get back to her, but he doesn't have many options, and RAF mascot Georgie needs his help. Meanwhile, Mrs Hall prepares a community Christmas celebration in Darrowby, while Siegfried and Carmody argue over who will be Father Christmas.

A memorial service is held in Darrowby to honour the war's fallen soldiers and Tristan tries to hide his emotion. He's keen to go for a drink with Siegfried, but finds himself at the bottom of his priorities. Meanwhile, James tells Mrs. Pumphrey not to give up hope in her quest to find a mate for Tricki, and plans a date night to get some time with Helen.

James is forced to take in Mrs Pumphrey's pampered Pekingese. Tristan prepares to return to university, but needs Siegfried's help to pay for his accommodation, but Siegfried insists he must first prove he is serious about being a vet. James treats the Aldersons' prize bull, and Helen rewards his efforts with some unusual home baking.

It's an important day for Tristan in more ways than one, as he celebrates his birthday and Siegfried gives him new responsibilities as a vet. Tristan has to withstand the pressure and succeed in the challenge set by his older brother before returning to Skeldale for his birthday festivities. Meanwhile, Mrs Hall reminds James that he needs to tell Helen some home truths.

When a familiar face from Helen's past returns to Darrowby, James worries that he has to vie for her attention and steps up to compete against them at Mrs Pumphrey's annual cricket match. The rest of Skeldale House are apprehensive as the game can be brutal. Siegfried tries his best to train James and get a reluctant Tristan to step in, but it's not looking good for their Darrowby Eleven team.

It is now spring 1939 and a potential world war looms. Tristan is now a qualified vet, while James enters a new stage of his life with Helen and at the practice. After being made joint business partner by Siegfried, James pushes to take on more responsibility via the Ministry of Agriculture's new bovine TB testing scheme, but its unexpected challenges risk pushing him to breaking point.