A seven-year-old boy named Amerigo who in 1946 leaves his impoverished family in Naples and gets on a train to go live with a wealthier family in the north as part of a postwar initiative to rescue children from poverty.

1946. Amerigo is seven years old and has never left Naples and his mother Antonietta. His world, made up of streets and poverty, however, is about to change. On board one of the "trains of happiness" he will spend the winter in the north, where a young woman, Derna, will welcome him and take care of him. Next to her Amerigo acquires an awareness that leads him to a painful choice that will change her life forever. It will take him many years to discover the truth: those who love you don't hold you back, but they let you go.