Married to a soldier who has returned from Afghanistan injured in body and mind, Stella Carey leaves the house every evening. During her nursing shifts, Stella writes letters for her patients to their loved ones - some full of humour, love and practical advice, others steeped in regret or pain, promising to post them after their deaths. Until one night Stella writes the letter that could give her patient one last chance at redemption, if she delivers it in time.