A mysterious nun makes contact with the OCS, while Adriel proposes a partnership to the pope. Lilith turns to an unexpected source for help.

After the Order sends out an urgent call, Beatrice and Ava connect with old friends in Madrid and stop by a museum. Jillian investigates an anomaly.

As a bizarre plague sweeps the city, Ava uncovers new revelations about Miguel -- and Adriel's methods. Lilith explores new possibilities.

Seeking Lilith's whereabouts, the sisters and Miguel visit Jillian. An unnerving discovery upsets Camila. Conflict erupts over Adriel at the conclave.

Ava and Beatrice jump into action when they meet an ally eager to take down a self-proclaimed prophet and his followers. Tragedy strikes at the convent.

The Order and their allies prepare for a showdown against Adriel at his new cathedral, but learn their adversaries have been making plans of their own.

After an intense battle, Ava's halo saves a life, while one of Adriel's followers has a crisis of faith. Camila finds herself behind enemy lines.

Ava visits the other realm and returns with a new plan to end Adriel's unholy charade -- but it will require superhuman strength and painful sacrifices.

As Ava contemplates starting over, she recalls being left to the tender mercies of the orphanage. The Sister Warriors suit up for a dangerous mission.

Ava experiences a come-to-Jesus moment courtesy of Mary, who pulls no punches as she shows her just how many souls have their own cross to bear.

Confused but excited by her newfound abilities, Ava soon realizes she's in over her head, but her need for a helping hand may be a blessing in disguise.

"The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds. " Infiltrating the Vatican to find a tomb hidden deep underground for a millennium? Hell, Ava may need a miracle to pull off this mission.

"Do not be afraid of what you are about to suffer. I tell you, the devil will put some of you in prison to test you, and you will suffer persecution for ten days. Be faithful, even to the point of death, and I will give you life as your victor's crown." In shock over the contents of the tomb, Ava no longer knows what — or who — to believe as she tries to divine the true history of the halo.

Hoping to find some answers, Ava puts her faith in science. Meanwhile, Cardinal Duretti's machinations sow seeds of dissension inside the Order.

While Mary squares off with Sister Lilith, Ava begins to open up to JC, and Jillian Salvius fires a warning shot at the Church.

After tasting the good life with JC, Ava crashes a swanky tech party with his friends. Mary goes gunning for the people behind the attack on her sisters.

Ava takes her first steps toward understanding the halo's power, but a baptism by fire at the hands of the Order leaves her feeling burned.

Secrets are revealed and a Sister Warrior mysteriously returns to the fold as Ava and her allies attempt to keep a sacred object out of the wrong hands.