In the early months of 1867, Seamus Delaney, a veteran officer of the Union Irish Brigade is now employed as a detective for the United States government. His duties and his love for his darling Emily have brought him back to the Nation's Capital in whose defense he had often fought during the Civil War. He is tasked with ensuring that the last of the known conspirators in the assassination of President Abraham Lincoln is brought to justice. When an attempt is made on his life, he is sure that the forces he has struggled with both before and since the official end of the War; violent secret societies, traitors and Copperheads, some of whom control powerful positions in local and national government, are determined to prevent him from carrying out his orders.