Off the southern tip of the Beara Peninsula lies Beanna Dubh, an island of savage beauty, its jagged cliffs lashed by Atlantic winds and infested by thousands of crows. Untouched by twenty-first-century advances, the islanders live under the strict rule of the church, while clinging to old superstitions of the crows as harbingers of disaster. To this desolate, unforgiving place Grizela Urquhart fled, seeking sanctuary from brutal bullying in her native Glasgow.

Forty years on, Grizela still remains an outsider—the eccentric painter viewed with distrust and barely tolerated. The feelings are mutual, for she has discovered there are as many secrets on Beanna Dubh as there are crows. When she stumbles upon the body of a young priest with a diabolical symbol drawn on his chest, the crows darken the skies, and Grizela is plagued by demonic whispers only she can hear. The islanders' suspicions fall on her, but she fears the answers lie in her tortured past.

Grizela scrambles to protect the innocent—a quartet of young girls she has taken under her wing. When she uncovers dark truths behind the girls' mysterious midnight gatherings, her grip on reality unravels and she is faced with an impossible choice: do the unthinkable to protect the girls, or come out of hiding to face the sins of her past.