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.

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.

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.

Everyone is determined to make Jimmy’s christening day special, while Siegfried is unimpressed when called up to Biggins’ farm.