All Creatures and Small Season 4 will begin in the spring of 1940, with change facing everyone at Skeldale House. James and Helen wonder when is the best time to have children and whether James will be called up to serve in the RAF. Tristan's absence is felt by all, but no one more than Siegfried, who tries to hold together his growing family, and himself, as he braves this new world. Mrs. Hall and Helen's friendship develops as they look to the future, and the arrival of new trainee veterinary student Richard Carmody causes trouble in the household.