In the wee hours one evening in a small Southern town, 17 grade school classmates got up from their beds, left their homes, and ran off into the night. As the stunned community grapples with the inexplicable-from the kids' suspected, fragile teacher (Julia Garner) to the dad (Josh Brolin) for whom the authorities aren't moving fast enough-the truths behind the phenomenon will reveal in jaw-dropping fashion.