Monk agrees to attend a dinner party at the lush home of arms dealer Daniel Alberton, whose daughter is madly in love with the American Lyman Breeland, who wants to buy munitions for the Union Army. But then the handsome Confederate Philo Trace appears on the scene and he just happened to have secured a deal with Alberton beforehand. When Alberton is found murdered and his daughter has run off to America with Breeland, Monk and Hester follow only to find that they may be chasing the wrong suspect...