James returns to Darrowby after serving in World War II to resume veterinary practice with Siegfried and Tristan Farnon; the practice must face the challenge of accelerating scientific progress in veterinary medicine.

David Powlett-Jones, a young Welshman, returns from the trenches of World War I disillusioned and suffering from shellshock. Accepted as a teacher at an elite boys boarding school, David fears he won't last. Luckily, the faith of the headmaster who hired him proves well-founded. Over the course of his 20-year rise through the ranks of the school, he finds and loses love with several women.