In the shadow of refinery smokestacks of Port Sabine, Texas, the golden girl, Mercy Louis, stands tall as the high school basketball star poised for greatness. Yet the pressure from her evangelical grandmother, Evelia, and the absence of her mother weigh heavily. As summer begins, a sinister discovery near the school sets off a frenzied witch-hunt in the town, revealing seedy undercurrents and family secrets. Alongside Mercy is Illa Stark, an outsider who uncovers a disturbing note hinting at Mercy's troubled life. Their fates intertwine when a mysterious malaise targets the town's girls, rendering them suspect. As Mercy's world crumbles, and the girls' plight worsens, Port Sabine's dark heart is laid bare, examining the harsh realities that young women face and the pressures that can fracture a community.