To help his friend, Geoffrey Horner, a gentleman radical who has become embroiled with the Chartists, evade murder charges in England, his barrister, Frederick Conyngham, attracts suspicion on himself and leaves for Spain, where he becomes an officer on the Royalist side in the Carlist War. Conyngham becomes immersed in intrigue when what he thinks is a love letter he has agreed to deliver, turns out to be a Carlist manifesto. His adventures take him to Ronda, Cuidad Real, Madrid, Toledo, and beyond.