John Whyte, disgraced son of an English Lord, has quit the British Army and come to America to join the Union cause. He is assigned to command of the 5th Michigan Cavalry under his former assistant, now Brigadier General George Custer. Whyte follows the dashing Custer into battle against the Confederate cavalry of JEB Stuart at Gettysburg, into the 1864 Valley Campaign, and is captured at the Battle of Cedar Creek. Incarcerated in the infamous Libby Prison in Richmond, VA, Whyte is under a death sentence for his actions in breaking the Rose Greenhow spy ring. If Custer's Cavalier is to survive the ordeal, it will take all his courage and cunning.