As the lamed Alderson bull is taken away to the butcher, James stops by the Alderson farm to give Jenny a kitten, in part as an apology. Helen tells James he did them a favor by telling the truth about the bull, and then Hugh arrives and gives Helen a kiss. After giving Jenny a chocolate bar, Hugh offers his own apology—to James, for pressuring him to lie about the bull. At least the whole situation has brought Hugh and Helen closer together, he says.
Back at the surgery, Siegfried is sick but refusing to acknowledge it. A package arrives for James, making Mrs. Hall and Tristan realize that his birthday is the next day. Tristan is supposed to be taking practice exams, but he uses planning a party for James as a distraction. He promises a date for James the next day, to help get James’s mind off Helen.
James has other things to occupy him, too: the Rudds recently bought a cow he gave a clean bill of health, and now she has developed an abscess in her throat. It could choke and eventually kill her. Since James oversaw a difficult calving for the Rudds before, they trust him completely.
While James is out, Mrs. Hall bakes him a cake. A line has formed at the surgery, as Siegfried has fallen asleep. Mrs. Hall pours some medicine into him and sends him to bed, putting Tristan in charge. With some surreptitious help from reference books, Tristan successfully treats all the patients. As Mrs. Hall sits down with him to force him to take his exam in the evening, Siegfried awakes. Seeing Tristan only just starting his exam, Siegfried decides to give up on his brother, not knowing that he worked the surgery all day.
Tristan doesn’t have a chance to fill in Siegfried about his good work. The next day, he simply tells his brother that he’ll have the exam for him by the evening, when the party he and Mrs. Hall organized for James starts. Siegfried goes to lie down.
But then Tristan is distracted again. Hoping to help James, who feels guilty that a cow he recommended might die, Tristan searches through reference books and comes up with an experimental but risky surgery to drain the abscess. Dick Rudd has stayed up all night rubbing a poultice on the cow but she’s only gotten worse, so James is open to Tristan’s idea.
Siegfried, however, thinks it is doomed to fail and forbids James from trying it, lest he put the cow through pain and give the Rudds false hope. James reluctantly follows Siegfried’s orders and tells the Rudds to send the cow to the butcher. They don’t blame him for the loss.
At James’s surprise party, Tristan introduces him to a pretty woman, whose friend is interested in Tristan. Jenny stops by with her kitten and asks James if the woman is his girlfriend; when he says no, she replies, “Good.” Helen arrives with Hugh to pick up Jenny and Hugh convinces her to stop in for a drink. Fine, she says, but don’t embarrass me.
She sees the woman kiss James on the cheek, just as Tristan’s old girlfriend Maggie sees Tristan with his arm around her friend. Helen asks James why he’s not happy at his own party. He tells her about the Rudd cow, and she encourages him to try the surgery. Follow your gut, not Siegfried’s rules, she advises.
Tristan follows Maggie and finds her upset. When he tries to talk about their relationship and asks why she said they were never serious, she replies that he’s not serious; no one thinks he is.
Both James and Tristan simultaneously decide to go ahead with the surgery.
When they go missing from the party, Siegfried quickly guesses their plan. Mrs. Hall drives him to the Rudd farm—he’s still sick and fully of medicine, a.k.a. whiskey. On the drive there, she argues with him, telling him he needs to give James and Tristan the space to be their own people. When they arrive, Siegfried chastises James and Tristan. James and Mrs. Hall plead with him, and Dick Rudd says he wants James to try the surgery.
So, using the car headlamps for light, James begins operating. Tristan and Siegfried offer advice while Mrs. Hall holds a lantern up to the cow’s neck. With James’s steady hand and Tristan’s good ideas, the surgery is successful. The cow is saved.
Tristan effusively praises James, telling him he pulled off a miracle in conducting an operation that no one has ever done before. James responds that he couldn’t have done it without Tristan. As they retire to the pub, they find Dick Rudd bragging about James.
Siegfried says the flu clouded his judgment; if he was in good health, he would have allowed James to try the surgery (sure). He half-apologizes to James, saying that he’s proud of him: the cow would have died in other hands. He promotes James to senior veterinarian—but don’t think that comes with a raise!
Siegfried shares fine Scotch with Tristan, telling him he heard about Tristan’s work in the surgery. It’s as close as Tristan will get to praise from Siegfried.
Hugh, in high spirits, buys a round of drinks for the whole pub while James thanks Helen for her confidence in him. As James speaks with Helen, news is broken: Helen is engaged to Hugh—Hugh wasn’t supposed to tell anyone, but couldn’t keep it a secret.
James is heartbroken, and walks outside. He is soon joined by Siegfried, Tristan, and Mrs. Hall, who walk him home. What a way to end a birthday.