The film is based on David McCullough's book about Harry S. Truman, our thirty-third President, and it follows him from his military service in World War 1 through his administration in the White House. Much of the film is told in flashbacks, while Truman is writing to his wife, Bess.
We first meet Truman on the campaign trail in 1948, when he was not favored to be reelected. His own party wanted to nominate Eisenhower, and he was polling well behind Republican candidate Thomas Dewey. Of course, we've all seen the famous photographs of Truman triumphantly holding up the "DEWEY DEFEATS TRUMAN" headline, but it's interesting to start months before then, when the outlook was bleak and Truman was going to have to shake every hand in America to be reelected.
There's no special agenda in this film, except to show us this fairly plain and simple man who never really sought greatness, but had it thrust upon him. There's not a whiff of obnoxious ambition about him. In fact, one of the most striking moments in the film - which is apparently something that really happened - is when he's brought to the White House after Roosevelt has died. Just before taking the oath of office, he passes Eleanor Roosevelt, and without thinking, stops to take her hands and ask her if there's anything he can do for her. Her response - "Is there anything we can do for you? For you are the one in trouble now."
One of my favorite scenes, though, is when Harry and Bess take their first steps in the White House and remark that this is their first house. I wanted to reach through the screen and hug them. We often forget that our leaders are human beings, too, and I think - no matter what your opinion of Truman - you can't really help rooting for him when he's presented not as a President or a President's legacy, but as a real, honest-to-goodness person.