When Leo is given the task of making a death mask of the old Duke, he soon realises the story of his death doesn't add up and begins a dangerous investigation, he approaches the local doctor to do a post-mortem, the doctor then tells Piero of Leo's concerns and Piero has the doctor shot to show Leo that the Milanese do use poison. This deception spurs Leonardo on to building a super weapon to avenge the doctor and fight the Milanese