Siegfried has an opportunity for his dream job: veterinarian for Darrowby’s racecourse. Horses are his passion, as he explains to the racecourse’s owner, General Ransom, during a trial day at the course. The general is skeptical of Siegfried, however, given that he has dealt more with carthorses than racehorses. But Hugh Hulton, Helen’s boyfriend and a wealthy landowner whose horse, Andante, is a favorite in the upcoming races, vouches for Siegfried, who has taken care of the Hulton horses for years.
When a horse goes down on the track, Siegfried has a chance to prove himself. The general wants to winch the horse off the track, but Siegfried curtly tells him no, letting the horse rest for a minute before hoisting it back up to walk off its fear. Later, Siegfried apologizes to the general: he did not mean to offend, but the animal always comes first. Siegfried was an army veterinarian during World War I, and has immense respect for horses after seeing them serve soldiers.
The general is trying out another veterinarian the next day, but will soon let Siegfried know if he has the job.
Meanwhile, Tristan has been sent to collect outstanding bills from the farmers Siegfried serves. After chasing a man who claims he doesn’t have the money on him into the pub and collecting his payment, Maggie, the bartender, suggests to Tristan that the pub is the perfect place to collect debts—but he himself must buy a drink. Tristan agrees—it helps that Maggie is pretty.
The farmers in the pub taunt Tristan about never paying for his own drink, so he buys them all a round. It’ll encourage them to pay up.
Mrs. Hall has offered to watch Jenny, the harried Helen’s younger sister, for the day. Helen is worried that Jenny can’t see a different future for herself than working on the farm, so Mrs. Hall tries to encourage her in other pursuits—unsuccessfully. Mrs. Hall takes Jenny for another day and manages to pique her interest in veterinary work. She gives Jenny a book to read on the subject. Later, she assures Helen that she’s doing her late mother proud in raising Jenny.
James is still dealing with crotchety farmers who are skeptical of his expertise. He diagnoses one of Mrs. Calvert’s cows with heat exhaustion, then is sent off to Hugh Hulton’s stables to examine a colicky horse.
Except the horse isn’t colicky—it’s suffering from bowel torsion, and has been for several hours. It’s too late to save it. James wants to put it down immediately to spare it any more pain, but the stable manager initially doesn’t believe James and demands a second opinion: it’s an expensive racehorse.
But they can’t reach Siegfried, so James makes an executive decision and euthanizes the horse—just as Hugh returns home. Hugh is both angry and saddened: the horse was Andante, the favorite at the racetrack. He demands that James leave immediately.
James cries in the car, then stops by the pub and tells his woeful story to Tristan. Tristan then realizes that he’s spent all the money he collected on rounds for the farmers. But he has a plan: he asks Maggie, who takes bets on the races, who the second favorite horse is behind Andante. He puts money on it.
Siegfried is in high spirits. He thanks Mrs. Hall for convincing him to take on James as an assistant: he thinks it made the general take him more seriously, and James has more than proved himself. Then Hugh arrives and complains about James’s euthanization of Andante. Siegfried defends his assistant, and when Hugh mentions involving a solicitor, Siegfried offers to conduct a postmortem tomorrow to confirm that James made the right decision.
Siegfried asks James how he is doing: a first euthanization is not easy. James is confident in his decision, but when he slightly hesitates in confirming it, Siegfried becomes serious. There will be consequences if James was wrong.
Tristan manages to avoid consequences for losing the money—at least for a bit—by fleeing Siegfried and hiding in James’s car. He convinces James to take him on his rounds. After they drive across a narrow bridge and run into a truck coming the other way driven by Helen, Tristan laughs at James’s awkward interaction with Helen. James admits that he asked Helen out. He at least takes heart in the fact that Helen and Hugh aren’t engaged.
Back at the Calvert farm, James is confronted by gossip: Mrs. Calvert calls him “Herriot the horse killer.” She wants Siegfried to look at another of her sick cows, but Tristan defends James’s abilities. James now doubts himself though, and struggles to diagnose the animal until Tristan points out a board in its stall that has been licked clean of paint. James figures it out: lead poisoning.
James is a talented veterinarian, as Siegfried’s postmortem of Andante proves: he did the right thing euthanizing the horse. Hugh is still upset, but Siegfried stands by James—to the point of losing his dream job. The general wants to offer Siegfried the position at the racecourse, but the horse owners are wary of Siegfried’s association with James after the situation with Andante. Siegfried can have the job if he lets James go—but he refuses. James is the best assistant he’s had, he tells the general.
The local farmers are now even more skeptical of James, but Siegfried decides to make them come round. James will be doing all of the rounds tomorrow—even for those people who request Siegfried.
And Tristan? His bet paid off—and he’s also rewarded with a kiss from Maggie. Siegfried never has to know he lost the money.