Lucio Battistini leads a simple life: he has a job, a water polo team to train two days a week, two children and a wife that he loves, a wife who has just thrown him out of the house for cheating on her. That's when he receives a visit from his friend Fritz, a friend who has no intention of leaving. In fact, Lucio will be the one to leave. Forever.
"My Friend Fritz" is the name Lucio has given to the terminal cancer that has left him with only three months to live. Passing through the initial stages of shock and desperation, Lucio decides he must live his last one hundred days to the full. He wants to win his wife back, teach his children how to swim, lose weight and arrive at the last appointment he'll ever have in good shape. But first he wants to travel with his family, to have a second chance with his children. He needs to leave his mark, and to let everybody know how happy he was, in spite of everything.