Dr. Baker posts an ad for another doctor, to relieve his workload (and Mrs. Oleson's constant pestering). He hires Dr. Caleb Ledoux, but doesn't count on him being black. The Ingalls are among the very few to accept Dr. Ledoux, as others are outright hateful and racist. Even Dr. Baker struggles with his prejudice and, to show his spite, gives the young doctor minor cases.
In the end, Dr. Ledoux is the only doctor available to call on a pregnant woman who is having labor complications. The woman's husband won't allow the doctor in the house (because he's black), and can only get to her when Charles knocks the man aside. Ledoux performs a successful surgery and delivers a son to the couple. A stunned and shaken Dr. Baker witnesses the surgery and concedes that only Caleb's and his superior training could have saved the woman's life.
Dr. Ledoux later angrily tells his wife he plans to leave Walnut Grove. But only Dr. Baker's emotional speech at church convinces the good doctor to stay.