Brother Anselm has kept spotless discipline for fourteen years: flagellation on Tuesdays and Fridays, the canonical hours recited on schedule, sermons on lust so pointed the blacksmith’s wife says they make her feel clean. Then he finds something bleeding in the November leaves, carries it home, and locks it in the root cellar under a lie about a broken gate latch.

He tells himself she’s a specimen. He builds a feeding stand at exactly twelve inches, trains her the way a falconer trains a hawk, and fills a ledger with clinical notes about antler growth and dappled skin that no priest should be able to describe so precisely. He calls her demon the way he says Amen.

She calls him by the name he discarded the day he was ordained.

Custodian details three years of confinement, confession, and a Summa theology, a collection of handwritten notes that was not intended to hold them. It tells the story of a man who aimed to civilize a creature but ultimately learned which of them was truly being imprisoned.