Adapted from Karen Dionne's best-selling novel of the same name, the heroine Helena (Daisy Ridley Daisy Ridley) ostensibly leads an ideal life with an excellent husband and young daughter, but she hides the shocking past: her mother was kidnapped as a teenager and she was born to a captive and abuser. Her father, Jacob Holbrooke (Ben Mendelson Ben Mendelsohn), is known as the "king of the swamp", imprisoning the mother and daughter in the wilderness for 12 years under the control of a tyrannical man until he is arrested and sent to prison. After Jacob escaped from prison and killed two prison guards, Helena realized the potential threat her father posed to her family and was forced to face up to her secret past and was determined to bring him down.