A man likes the girlfriend of his best friend, but he never expresses himself. Once, he incidentally finds a locked box of his divorced mother. There are many old letters and photos inside. His mother is still upset about a previous relationship. Through the story of his mother, this man learns to let things go ...單親家庭成長的阿雲，對女孩珊珊甚在意。阿雲在零晨聽到母親啜泣，卻不敢問個究竟。學校裡，好友道出欲與珊珊分手，被珊珊聽到了，阿雲卻只能在她身旁默默站著給予支持。阿雲在家清潔時，發現母親衣櫥裡的一個帶鎖木匣子，匣子裡有舊信件及相片，阿雲突然醒覺事情不能強求。母親與珊珊都因想不開，傷害了自己……
