The film starts with Henry Griffin learning from his oncologist that his cancer has spread and that he only has one year, two at most, left to live. This discovery starts him on a journey of self-reflection which includes starting a novel and taking a psychology class at New York University. In this class, he meets Sarah Phoenix. He asks her on a date and after hesitation she comes. Then the two of them goof around and eventually stay up all night together watching the sunrise. Griffin believes they are close but Phoenix doesn't show as much interest. Although Phoenix sends Griffin the occasional mixed signals, the two team up for a whirlwind of adventurous and almost childlike activities, such as painting graffiti on a water tower. However Phoenix doesn't want to hurt Griffin or herself by falling in love because she's too weak to deal with it as she too has cancer and is also short of time. One day while at Griffin's house after their adventure, while cleaning she comes across his books on dying and "living life to the fullest" and comes to the conclusion that Griffin knows she's ill and is being nice only out of sympathy. She storms out and after their confrontation Griffin explains that the books belong to him and he too has cancer. This causes the two to fall ever more deeply for one another, and their relationship deepens. Together, they strive to make the most of their last days of life. However while exploring and making the most of their last days, Griffin explains how when he gets seriously ill he will just leave and he wishes for her to not come looking for him because it's something he feels he must do himself. But Phoenix is first to get sick and uses Griffin's same words against him. This deeply hurts Griffin and causes him to overact. Later, however, after realizing he was wrong, he decides he wants to spend the last moments of Phoenix's life with her anyhow. Griffin makes a last 'Christmas' for Phoenix, as it is her favorite season and it would be their last holiday together. The movie ends with two men repainting the water tower, covering Griffin's graffiti heart proclaiming his love for Phoenix.
