A rosary in one hand. A dagger in the other.

Sister Magdalena never heard of the Catherinite nuns until the day she faced her own death sentence.

Rome, 1562. It's the era of the Index of Banned Books and the Roman Inquisition. Kings still burn heretics. The worst threats come from within the Church itself

Only seventeen, Magdalena killed a priest who tried to rape her within the walls of her convent. His powerful family will see her executed, and then they'll destroy her mother and young sister.

Instead, the pope makes an offer. To save her life and protect her family, Magdalena can disappear into a secret religious order, one with a demanding physical regimen to go along with the prayers. She'll pray the psalms and learn to climb walls. She'll sharpen her mind and fine-tune her body. Perfected, she'll infiltrate the Council of Trent.

Magdalena's order slips through cathedrals and palaces at the council, the Pope's silent operatives. They act as bodyguards for the cardinals They gather intelligence. If they find heresy, the penalty is death.

But when one of the pope's own men is named a heretic, Magdalena must decide how far she'll go to protect her church.