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.

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.

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.

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.

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.

James and Helen are keeping a secret, and following a visit to the Crabtree’s Farm, Carmody is challenged with learning how to be a vet outside of his books. The new farmers have a worrying illness amongst their herd and James wants to help them in any way he can.

When new vet Richard Carmody joins the practice, James feels his place by Siegfried’s side is threatened. Conflicts come to the surface at Mrs Pumphrey’s community tea party.

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.

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.

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.

With World War II underway, Siegfried takes up the slack at the surgery. James faces an uncertain future when he is grounded at the RAF. Mrs Hall and Helen consider their contribution within the community, and Carmody is eager to step up.

Skeldale House descends into chaos with the arrival of Siegfried's wayward brother Tristan. Helen provides James with a reason to stay in the Dales.

Fresh out of veterinary college in 1937, James Herriot struggles to find work in his Depression-struck home town of Glasgow. Seeking new opportunities, he pursues a position in the remote village of Darrowby working for eccentric local vet Siegfried Farnon, who is less than impressed by his early efforts. However, a difficult calving gives James a chance to prove his worth.

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.

James needs a crash course for fatherhood. Mrs Hall referees between Siegfried and her new boss, Mr Bosworth, as they fall out over some of Mr Bosworth's safety tactics. Helen is concerned about the influence of Jenny's new friend Doris.

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.

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.

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.

Tristan and Carmody can't see eye to eye, but a quest to Pumphrey Manor might just bring them together. Helen tries to support James when unresolved feelings resurface.

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.

After receiving outstanding exam results, Carmody is offered a position in a research program in London, but he wants to stay at Skeldale. An exhilarated Mr Bosworth summons Mrs Hall to examine a piece of debris that has dropped from a plane into a remote field.

Siegfried hires an experienced bookkeeper, but her efficient approach doesn’t suit everyone. James and Helen arrive at a big decision, and a ferret presents a challenge for the practice.