The tragic saga that is the West Memphis Three case has already been documented in non-fiction film, and now it's getting fictionalized treatment in "Devil's Knot" by director Atom Egoyan.

In the 1994 case, three teen boys were convicted of murdering three younger boys in what the prosecution called a Satanic ritual. But many believed the teens to be innocent and rallied the support of celebrities to raise money for their legal defense. In 2010, their convictions were overturned, though they were not entirely cleared of wrongdoing.

In the first trailer for "Devil's Knot," Reese Witherspoon plays the grieving mother of one of the murdered boys. When her son is found dead, she wants justice, which seems she'll get when the police quickly arrest the teens.

But an investigator (Colin Firth) who's come to town finds compelling proof that the teens didn't do it. He's disturbed by the local police's focus on satanic activity and cults, and works to try to clear the teens' names. "Would you want three more families to lose their children, too?" he asks.

"Devil's Knot" premiered at the Toronto International Film Festival and goes into wider release later this year.