It's 1948 and Eliza Kendall's father has just dropped her off at Prescott House, a home for unwed mothers. Pregnant and alone, Eliza finds comfort in her three roommates, whose friendship gives her hope despite ongoing abuse from a bitter headmistress. Caught between adolescence and womanhood, the friends seek refuge in what lies beyond the veil of sleep and dreams, to the hidden passages in the house itself, rumored to be part of the Underground Railroad. While exploring, the girls discover a plot to hide the bodies of other pregnant women. To survive, they must lean on each other and the wisdom of those who have come before them-the butterfly sisters.

But is their bond more powerful than the threats they face?