This entire episode is about Eleanor and Franklin, as by the time the show began, Teddy's enthusiasm for politics had waned...since he was dead.
As for Franklin, in the very early 20s he contracted polio and much of the show is about his fruitless battle to beat the disease. However, using his strength of character, he threw himself into trying to beat it...as well as projecting a positive public image. Eventually, he was to return to public life and was in charge of the 1924 presidential campaign as well as making very important speeches for the Democratic nominee. Then, in 1928 when Al Smith ran for president, Franklin unexpectedly not only ran for Smith's office but took it seriously and was an extremely popular governor--so popular that he was in a great position to run for president in 1932. The episode ends with his election...huzzah!
As for Eleanor, the 1920s marked a HUGE break with Franklin and as Franklin dealt with his polio, she embarked in public service campaigns as well as creating a life independent of her husband. I don't know if it was intended, but the show seemed to imply that Eleanor was extremely close to some of her lady friends...very close. They never said she was gay or a bisexual, though I am sure many viewers assumed that when they read some of Eleanor's very tender letters to one of her lady friends.
Overall, an inspiring but sad episode. While both Roosevelts seemed to blossom, they did so completely separately and seemed to have their own respective lives. Another very well made episode by Ken Burns and his crew. Educational, interesting and well made.