Fast asleep and dreaming of a serene lake in the remote wilderness, Mary Fulmer is suddenly awakened by the rings from her phone in the dead of night. She reluctantly answers the call only to discover that someone - or something - sinister is on the other end. In an instant, Mary realizes that she is alone and must decide whether to stay and defend herself or leave and confront the darkness that lurks quietly within the walls of her home and relive the moments that continue to haunt her life and dreams.