Brackston marries the suspicions of an isolated Welsh community with the appearance of a young woman who hasn't spoken a word since childhood. Raised by her mother in a town that sees her as an object of scorn, the silent Morgana loves her mother deeply and misses the father who left suddenly when she was small. Her mother hopes that marriage to a widower, drover Cai Jenkins, will allow Morgana to start over in a place where her history is unknown. The secret kept between mother and daughter is that the girl does have unusual powers, abilities that might be interpreted as those of a witch.

Intrigued by his lovely, silent bride, Cai has wed because marriage is required of a drover, though he undertakes the union not reluctantly. Conscious that he must tread this new relationship carefully, he intends to slowly woo his bride to his bed. Theirs is a practical life, the hard physical labor of gathering and tending herds to bring to market, everyone toiling cooperatively in a close-knit community where unpredictable weather and disaster can change family fortunes. While Morgana wonders at Cai's reluctance to bed her, she is also soothed by his lack of demand (a seed to be nourished as the tale progresses).

Though Morgana is joyfully embraced by Mrs. Jones, the housekeeper, trouble arrives with her introduction to the local minister, Cadwaladr, and Cai's wealthy lady friend, Isolda Bowen. Morgana immediately senses an enmity around her, the presence of a dark power. Acutely sensitive to threat, she struggles to understand the origin of this malevolence and the extent of her own power in defending herself, aware that she faces an enemy that would see her gone from this place.

Here Brackston reveals fragments of Morgana's past, setting the stage for her eventual confrontation with the evil that threatens both new bride and her husband. What has only been implied now takes form in an ugly encounter with the minister and later with Isolda Bowen, the true stakes of the contest laid bare. An already eerie tale takes on the attributes of the otherworldly, Morgana's struggles locked inside her mind, trapped inside a body incapable of uttering words. For all of her husband's best intentions, Morgana is left on her own. Only Mrs. Jones recognizes the enormity of the stakes should Morgana fail.

Naturally adapting to the handling of Cai's wild ponies, Morgana is included on the drive to market, unaware that the dark power accompanies them, sewing tragedy and suspicion along the way, inciting gossip that Morgana's presence has cursed the drovers. A stronger force than Morgana's is at work here, coveting what the girl has gained by virtue of her marriage. On Cai's family land, Ffynnon Las, is a pool, the Blue Well, which Mrs. Jones describes as a witching well, a place where curses may be cast. As Mrs. Jones intuits Morgana's powers over time, she reveals a hidden book: the Grimoire of the Blue Well, of infinite value to the one who possesses its secrets and equally dangerous in the wrong hands.

While a hapless husband stands by his wife in her trial even though visited with a deadly curse, he falls hopelessly in love. Yet Morgana must face this enemy alone, to feel the breadth of its power and survive every attempt to annihilate her. The final confrontation in a secret chamber is a scene of evil incarnate, one force pitted against the other in a fiery clash that calls forth a demon shed of human face. Good and evil stand face to face in a final showdown. Brackston's imaginative story is fascinating, polished and intriguing, as is her silent heroine.