Mr. Smith Goes to Washington is a drama about American government. Governor Hubert "Happy" Hopper (Guy Kibbee), about to pick a replacement to fill the unexpired term of a deceased Senator. His corrupt political boss, Jim Taylor (Edward Arnold), wants Hopper to choose his handpicked stooge. Popular committees want him to name a reform candidate. The governor's children want him to select Jefferson Smith (James Stewart), the head of the Boy Rangers.