May 5, 1993. West Memephis, Arkansas. Three young boys playing in the nearby woods never come home for dinner. In the rush to find and convict the killers, police focus on a trio of teenagers suspected of devil worship. As the mother of one of the murdered boys (Reese Witherspoon) tries to come to grips with this unspeakable tragedy, she is desperate to believe that the killers have been found and will be brought to justice. It is only when a private investigator (Colin Firth) reveals that the evidence doesn't all add up, that the community is forced to face the reality that the true killer might still be out there.