Clodagh begins by telling the story of her mother, Agatha, "a tinker; a traveler girl who had married a wealthy man." At age 15, ruffian Agatha marries 30-year-old invalid Frank Sheehy because "when he saw her he felt his heart steady in his chest, and a surge of strength come into his body." Like a spoiled child, she is drawn to all the pretty things he has to give her. Love, however, does little to cure Frank. He dies within the year, two weeks before Agatha (now a 16-year-old wealthy widow) finds that she is pregnant.
As wicked sisters-in-law will do, Frank's spinster sisters see through their grief enough to realize that the sight of pregnant Agatha disgusts them, so they banish her to a decrepit mansion across the country. There, Agatha, with the help of the trusty (if crusty) housekeeper, gives birth to twin daughters. One, Clodagh, bursts lustily on the scene. The other, Margaret Mary, needs to be coaxed into life, being "born with no instinct to breathe." Her life is destined to be short, but illuminates the world of those around her.
Even with two children to weigh on her mind, Agatha can't quite fit into her relatively comfortable life. She's more drawn to the wanderings and campfires of the tinker's itinerate existence. Backing away from her daughters, she screams, "I had no bloody girlhood." The daughters start to hear the nightly rumblings of a man Agatha tries to explain away as the ghost of their father. Well, the girls are innocent, but not stupid.
It seems that Agatha carries some past-life baggage of a bestial nature. She's repeatedly identified (OK, maybe once too often) with the myth of the Irish selkie. The selkie, born a seal, hears "the cries of a fisherman that lured [it] ashore." A reading of the selkie narrative explains, "He took my sealskin from me and made me his, then brought me to his home. He married me and we had a child together."
As for Agatha, existence on shore proves to be humdrum. The selkie finds her sealskin and slips back out to the sea, having "grown tired of being human" and dreaming of "a second chance at grace; pushing the seam between worlds, looking for the glimmer of an underwater room."
Although the selkie myth fits Agatha all too well, McBride resists letting it guide the novel into predictability. As Agatha fades, Clodagh emerges to pick up the pieces and make sense of both her own and her mother's messy lives, ultimately discovering the truths surrounding herself to be even more shocking than those entangled with her mother.
McBride claims that an interest in mythology inspired this novel. As one of the later characters explains, "People make such magical stories to soften the hardness of the world."
Though magic and storytelling must be handled gingerly, McBride capably weds the two.