In a small town in the United States, a four-year-old girl named Amanda suddenly disappeared. Her aunt and uncle found private detective Patrick Kenzie (Casey Affleck) and commissioned him to investigate the disappearance of their niece. Patrick Kenzie and his girlfriend and work partner Angela (Michelle Monaghan) began a difficult investigation. As the investigation deepened, they found that Amanda's mother Helene was a real drug addict. She seemed to care more about drugs than her daughter's disappearance. After the investigation was launched around her, drug dealers, fraudsters, and child abusers gradually surfaced. Detective Remy Broussard (Ed Harris) and police officer Jack Doyle (Morgan Freeman) also joined the investigation of the case, but Amanda's name became more and more out of reach. Patrick Kenzie also stood at the crossroads of morality and began to think about what it means to "uphold justice."