Recently retired, sweet, emotionally numb Harold Fry is jolted out of his passivity by a letter from Queenie Hennessy, an old friend, whom he hasn't heard from in 20 years. She has written to say she is in hospice and wanted to say goodbye. Leaving his tense, bitter wife Maureen to her chores, Harold intends a quick walk to the corner mailbox to post his reply but instead he becomes convinced he must deliver his message in person to Queenie - 600 miles away - because as long as he keeps walking, Harold believes that she will not die.