Nineteenth-century Dublin is a city riven by the greed of an emerging middle class and the unspeakable poverty of the poor. Alicia Buckley and Sarah Rooney, growing up there, embody that divide. Despite their different backgrounds, the girls enjoy an extraordinary friendship, so when Sarah falls pregnant, and is thrown out by her father, Allie doesn't think twice about joining her friend in exile. Neither woman is prepared for the deprivations she will face. Pursuing Sarah's soldier lover, they make their way, with baby James, to Kildare, where they become part of a community of outcast women, known as the Wrens of the Curragh. Reviled in the local town, the women live rough, savage lives on the outskirts of the army camp. But there is also sharing and trust, through her work as the community's doctor, a liberation for Allie from the stifling expectations of her family. Tragedy, however, forces them to travel to America, but a final twist of fate means that only one woman will reach that brave new world.