With Tristan Gone, All Creatures Great and Small Homes in on Family

Callum Woodhouse's Tristan Farnon doesn't appear in All Creatures Great and Small Season 4, but his absence casts a long shadow over the six-episode season (and the accompanying Christmas special). With Tristan gone and Britain losing the war against the Nazis, the residents of Skeldale House struggle to keep their anxiety in check, and both their home and the veterinary practice are thrown into disarray as a result. To get through it, they must lean on one another like never before — and if there's one thing Ben Vanstone's British drama continues to do consistently, it's to remind viewers that there's power in numbers, particularly when coupled with good intentions and a hopeful outlook.

Over the course of the series, as brothers Siegfried (Samuel West) and Tristan overcame their decades-old conflict, James Herriot (Nicholas Ralph) and Helen (Rachel Shenton) navigated their relationship, and Mrs. Audrey Hall (Anna Madeley) considered her role beyond caretaker, these characters have coalesced into an unorthodox but mighty family unit. While the show's "chosen family" ethos has been present since the beginning, Season 4 is more explicit in reinforcing that theme. The new installment deemphasizes the animals of the Yorkshire Dales to instead focus on more human concerns, with each character facing obstacles that either threaten to take them away from their home, or fundamentally alter their place in it.

When it comes to honoring one's familial obligations, James' arc is the most obvious. James spent last season debating whether to enlist in the war effort (despite veterinarians being a reserved occupation and thus exempt from the draft), but now, in 1940, he finds himself in limbo as he waits to hear whether he'll be called up to the Royal Air Force. He and Helen are keen to have a baby, but the possibility of his sudden departure, as well as their concerns about bringing a child into a world gripped by crisis and cruelty, leave them contemplating an uncertain future.

James' sense of duty — as manifested in his patriotism and his tendency to put the animals before himself — has always been his dominant character trait, but when Helen becomes pregnant, he begins to have doubts about whether he's made the right choice. That tension, combined with All Creatures' growing acknowledgment that James' altruism doubles as a form of selfishness, complicates the show's most simplistic character in an unexpected way. It also gives Ralph a bit more to chew on than in seasons past, when James' biggest worries were managing Siegfried's moods and identifying the mystery disease ailing a farmer's herd of cattle.

The Scottish vet has never been All Creatures comedic center, but with his storyline so firmly rooted in the grim realities of World War II, it's up to the others to deliver the feel-good moments for which the show has become known. In seasons past, this job fell to Woodhouse, who played Tristan with a delightful impishness that brightened up any scene, including his frequent battles with his older brother. Season 4 tries a few different things to fill the void created by Tristan's absence — including adding new character Miss Harbottle (Neve McIntosh), a bookkeeper who runs afoul of veterinary code with her profits-before-patients mentality — but early episodes fail to recapture his unique charm; consequently, the season gets off to a slow start as both the characters and the series attempt to find their footing.

However, things pick up when Skeldale House welcomes veterinary student Richard Carmody (James Anthony-Rose), who has a strong command of the latest developments in veterinary science, but is sorely in need of practical knowledge and social awareness. While Richard lacks the people skills that make Tristan so endearing, he fulfills a similar role as the practice's punching bag. The season finds no shortage of humor in the young vet's ignorance, which becomes a source of conflict with everyone from the local farmers to Darrowby grand dame Mrs. Pumphrey (Patricia Hodge), whom Richard offends when he asks why she "treats [her] animals like people." (How dare anyone say such a thing about beloved Pekingese Tricki Woo.)

And though Siegfried is initially frosty to Richard — he's loath to replace Tristan in any way — he comes to see the student as a stand-in for his brother. In Richard, Siegfried discovers an opportunity to correct his harsh mentorship toward Tristan. He patiently works with Richard on his bedside manner, teaches him how to drive, and reminds him that their job involves not just treating animals, but evaluating and respecting their owners. As always, Siegfried's kindness is buried under a layer of condescension, but four seasons in, his vulnerability sits closer to the surface, making it easier for West to toggle between the two sides of the character, the gentle and the surly.

Season 4 doesn't just expand the All Creatures family in the literal sense. If the past three seasons centered on the Farnon brothers' relationship, this outing emphasizes the sisterhood between Audrey and Helen, who have become one another's closest confidante. Both women get rich storylines — Audrey begins the process of divorcing her estranged husband and considers what's next in her romance with Gerald (Will Thorp), and Helen grapples with the looming changes in her life — but Madeley and Shenton do some of their finest work when they share the screen, specifically in later episodes as they come to question their respective roles in the house.

Despite all that happens elsewhere, including advancements in the ongoing Siegfried-Audrey-Gerald love triangle, Audry and Helen's growth, as individuals and as friends, becomes the story of the season, and their bond opens up a world of possibilities for the drama's not-yet-announced (but likely) fifth season.

As with any show that continues without a key cast member, All Creatures Great and Small feels different without Tristan. Though he's undoubtedly missed, Woodhouse's absence opens the door for Vanstone and the cast to try something new — something that's familiar enough to be comforting, but still offers a fresh look at this unconventional family and all they have to fight for.

All Creatures Great and Small premieres Sunday, January 7 at 9:00 PM ET on Masterpiece on PBS. Join the discussion about the show in our forums.

Claire Spellberg Lustig is the Senior Editor at Primetimer and a scholar of The View. Follow her on Twitter at @c_spellberg.