Becca (Olivia DeJonge) and younger brother Tyler (Ed Oxenbould) say goodbye to their mother (Kathryn Hahn) as they board a train and head deep into Pennsylvania farm country to meet their maternal grandparents for the first time. Welcomed by Nana (Deanna Dunagan) and Pop Pop (Peter McRobbie), all seems well until the siblings start to notice increasingly strange behavior from the seemingly charming couple. Once the children discover a shocking secret, they begin to wonder if they'll ever make it home.