A talented young pavement artist named Tomaso turns up looking for an apprenticeship at the workshop of the artist Verrochio, where Leonardo is already an apprentice.

Lorenzo's father Piero de' Medici masterminds the theft of Leo's notebook. However, it proves to be no use to him because all the formulae and calculations are written in code.

Leonardo has been working on a massive pair of wings, with which he believes he's going to be able to fly. Convinced he'll die in the attempt, Tomaso does everything possible to stop him, but, as ever, Leo is determined and certain that the wings will work.

Leo and Tom have an unusual commission. They are to paint the wedding portrait of Petronella, the unhappiest bride they have ever seen. Small wonder when they meet her husband to be, the evil loan shark Lucio, and understand that Petronella is sacrificing her own happiness to save her father, who is heavily in debt to Lucio.

Tom is really a girl called Lisa, who has chosen to live as a boy to fulfil her ambition to paint. Hanging out in all-male company can be a strain, especially when Leo never notices her interest in him. Leo falls in love with Lorenzo's spoilt cousin Valentina instead.

Lorenzo smuggles Leo into the palace to show him an extraordinary object - a plain box, which produces an amazing light show. Leo creates a replica and they swap the boxes so Leo can discover how the original works.