A mysterious man asks Leo for help, claiming that he knows the location of a huge treasure and that his brother went missing trying to find it. Leo follows the cryptic clues across the city, whilst Lisa and Mac become concerned that the man is lying, they too try and follow the clues, failing at the first one and going hopelessly in the wrong direction. Once they are returning to the workshop, they again find the man who went off with Leo, he tells them that Leo has died on the hunt (which is a lie and both Lisa and Mac realise this) so they trick him into leading them back to Leonardo and go on a rescue mission for him. Meanwhile, Piero kills his own cousin so that he can be Duke of Florence.