I think I like this one better than its remake, the famous "Mr. Smith Goes To Washington". Now don't think I just spoiled this one for you, because really, other than the theme, Mr. Smith has a very different script when you dig into the details. Such a film as this could not have been made after the precode era.
Buttons Gwinett Brown (Lee Tracy) has just been elected to a house seat. He's the descendant of a hero of the American revolution, but unlike James Stewart's Mr. Smith, he is no babe in the woods. He knows he was elected by bought votes and via corruption, but he plans to double-cross the double-crossers and help stamp out corruption in Congress, and doesn't care if he's a one-termer. He says all of this when he visits the Bonus Army that is encamped outside of Washington - the WWI vets that are in a sit down strike demanding the bonus they were promised years ago.
Buttons may know what he wants to accomplish when he arrives in D.C., but he doesn't know how to accomplish it. I had my doubts about Lee Tracy playing a Washington reformer, but he was absolutely perfect in a role that requires absolute cynicism intertwined with patriotism. This thing is precode and frighteningly relevant to today's Washington with Tracy's Buttons Gwinett talking about all of the lobbyists attached to Congress and voter apathy allowing the system to go on. There are suicides, murder, bold faced bribes, a man who would be king -literally, and the only boy scouts in this film involve a troop briefly marching through a train station past a group of very self-satisfied women wearing banners saying "No Saloons" the year before Prohibition ends.
Constance Cummings is the closest thing to Jean Arthur's counterpart in Mr. Smith, but here she is a Mary Antoinette like granddaughter of a senior senator, all caught up in Washington society and appearances - at first, that is. Strangely enough Walter Connally is playing a very old man here, at only age 45.
I'd highly recommend this one. The end kind of leaves you hanging, but remember this was released when unemployment was 25% and before FDR. The nation was kind of hanging at that point too, not knowing what was going to happen next.