Ian and his 10-year-old daughter Mattie are struggling with the passing of Kate--wife and mother--after her long battle with cancer. When Ian finally opens a letter Kate handed him before her death, he is surprised at the request inside: that he and Mattie travel across Asia while opening a series of letters from Kate, one at a time. As they complete each stage of the trip, they tie paper wishes to trees, which helps them come to terms with their loss.