Giovanni Battista Pergolesi is twenty-six years old and consumption no longer gives him much time to live. He works with the few forces he has left on his masterpiece, the Stabat Mater, in a cell of the Capuchin convent in Pozzuoli. In the last hours of his life, his thoughts return to Jesi, the small town in the Marche from which he left twelve years earlier to go to study in Naples, and to that day in early March when he took a long excursion together with the spirit of his little sister Rosa, died at the age of two, to go to greet her spiritual father at the abbey of Chiaravalle and to fix forever in her heart the places of her childhood. A journey through the Marche countryside to discover himself, from which he will draw inspiration for his immortal works and which will mark the passage from the anguish of a difficult childhood to the awareness of being called to a great, tragic destiny.