On the night of the Summer Solstice in 1999, nine-year-old Roisin O’Halloran marched into the Hanging Woods, the mysterious copse that had inspired fear in decades of children in the small Irish town of Bannakilduf. She was never seen again. Twenty years later, two women are drawn together to discover the truth of what happened to Roisin: Roisin’s older sister, Deedee, a rookie cop who’s barely hanging on to the appearance of keeping it all together, and Roisin’s childhood best friend, Caitlin, a petty criminal who was the last person to see the young girl before she disappeared, now returned to her hometown after her mother’s death. Reluctantly brought together after decades of mistrust, Caitlin and Deedee must reckon with their shadowy pasts, the monsters that still haunt them, and the role they each may have played in Roisin’s disappearance.