Holly and Gerry are a married couple who live on the Lower East Side of Manhattan. They are deeply in love, but they fight occasionally. By winter that year, Gerry suddenly dies of a brain tumor, and Holly realizes how much he meant to her as well as how insignificant their arguments were.
Deeply distraught, Holly withdraws from her family and friends out of grief until they descend upon her on her 30th birthday. They are determined to prod the young widow to face the future and explore what her life choices should be. As they rally around Holly and help organize her apartment, a cake is delivered, and with it is a message from Gerry. It proves to be the first of several meaningful messages — all ending with "P.S. I Love You" — which he had arranged to have delivered to her after his death.