A copperhead is a turncoat – a northerner who sympathises with the South. Captain Nate Starbuck, forced out of his beloved Legion by the enmity of its founder, General Washington Faulconer, becomes caught up in a dangerous double game of espionage.

He is given no choice but to travel from a prison cell in Richmond, Virginia, to the secret centre of the high Northen command in a desperate attempt to thwart Yankee strategy which threatens to overwhelm the South.

Starbuck plays a difficult and complex game of bluff and betrayal in a winner-takes-all effort to save his own life and return to the Legion – but at a high cost to his personal and professional loyalties as a friend and a man of war.