In Milan, in 1506, Leonardo da Vinci is arrested on charges of having poisoned Caterina da Cremona. After declaring his innocence to Stefano Giraldi, an official of the Podestà, Leonardo recalls his days as an apprentice in the workshop of Andrea del Verrocchio, where he first met the model Caterina.

Leonardo moves to Milan, determined to obtain the patronage of the Regent Duke Ludovico Sforza. When reality proves to be less attractive than expected and Leonardo is asked to devote himself to a great theatrical performance instead of a painting, it is a new encounter that helps him to free his imagination, allowing him to see in the theatrical production a great opportunity.