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.

As Leonardo's achievements are recognized and his reputation grows, one risky decision could destroy everything he has worked for. When an unforeseen situation further undermines his reputation as an artist, he sets his sights on the Duchy of Milan and leaves Florence.