In November 1989, Emily Patterson is enjoying a quiet life in West Texas, but loneliness nips at her heart. Then a red envelope appears in her mailbox. It's a letter from Mark who declares his love for her, and promises to come to her if he makes it home alive. But who is Mark? She flips the envelope over, but there is no return address and it is postmarked 1968. Over the next few days more letters mysteriously appear in her mailbox and odd things...