When teenagers Danielle and Gracie Sullivan take a clandestine car trip to visit their friend in Montana, little do they know it's the last time anyone will ever hear from them again. The girls and their car simply vanish. Cody Hoyt, who's just lost his job and has fallen off the wagon after a long stretch of sobriety, is in no condition to investigate. But his son Justin, who the girls were going to visit, and his former partner, Cassie Dewell, convince him to drive south to their last known location. As Cody makes his way to the remote stretch of Montana highway where the girls went missing, Cassie discovers that there have been scores of similar disappearnaces in the state. There's a serial killer out there roaming the highways, and Cody and Cassie must find him before he takes more lives.