Samantha "Sam" works at a crisis hotline where she listens to strangers and helps them deal with their pain. It's a pain she knows well since the hotline saved her life once when she lost her sight and didn't know how to live in a world of darkness. On her last night on the job, Sam receives a terrifying visit from one of her regular callers who feels betrayed that she's leaving him. This man is no ordinary caller. He's a sadistic serial killer she's unknowingly been keeping from killing himself for over a year. With only a skeleton crew on the graveyard shift, very little stands between him and Sam. He's come for her, and he won't let anything or anyone stand in his way. Will Sam survive the longest, darkest night of her life?