Warrior Nun literally starts with a bang, as the beginning scenes follow armed nuns retreating from battle into the morgue where Ava's body is being processed. Sister Shannon, the current halo-bearer, dies from incurable wounds and the nuns must hurriedly remove the halo and place it into another vessel before their assailants can capture it. Enter Ava's dead, lifeless corpse.
Shotgun Mary, a gun-toting member of the order with no care for religion, is distraught over Shannon's death, setting off her season-arc to find the party responsible for the attack. Whenever Shotgun Mary reminisces on her time with Shannon, or pleads for more time to crack the case, there is a glimmer of love in her eyes, and it isn't just the friendship kind.