John "Kit" McKittredge is a young Federal officer from Maine who is terribly wounded in one of the first battles of the Civil War. Still unfit for active duty after nine months in hospital, he is recruited by an unorthodox colonel named Valentine Burdette to work in the Provost Marshal General's office in Washington. The beleaguered Capital, now swollen to seven times its pre-war population, is filled with saloons, brothels, spies, thieves and murderers...