«In this second part, a woman has been found strangled in front of a local church. On her lap, a bag full of coins and a note «For masses for her soul» is found. In a nearby convent for young society ladies, the chaplain is having «unconventional» encounters with his novices. Captain Alatriste will soon discover how these two facts are connected by an entangled net of power, faith, and death.»

Flanders, 1625. After his tussles with the Inquisition and the intrigue of the Spanish court, Captain Alatriste has returned to the mud and desperation of the long war in Flanders. This is Iñigo's first experience of war and the realities of hand to hand combat. It is on the battlefield that he will finally have the chance to become a man and prove his worth. The troops are weary and ill-nourished and the winter has been long. As Spain sinks ever further into depravity and corruption, the soldiers have not been paid and must survive by whatever ways they can. Mutiny is in the air, on the lips of every Spaniard but they are strong and their famous iron discipline has brought them many victories against the Calvinist forces of the heretics. Reputation, honour, and the glory of Spain will keep them in the fight, but for how long? Meanwhile, the Captain's trusted friend Quevedo's star is rising at court and he keeps Alatriste appraised of the machinations of his arch-enemy Luis de Alquézar and the notorious assassin with the black heart, Gualterio Malatesta.

A desperate father hires Alatriste to rescue his daughter from a convent where a powerful priest is said to be using the girl as his personal concubine. Soon Alatriste discovers that he has become part of a religious and political conspiracy that leads all the way to the highest levels of the Inquisition.