Fireball (S01E12)

Piero invites Leonardo to his palace, proposing a collaboration on one of the inventions from Leonardo's notebook, which he believes could be groundbreaking. However, Machiavelli mistakenly interprets their project as a deadly bomb intended to assassinate the Duke of Florence during his birthday celebration. When Leonardo unveils the invention, it turns out to be a mere toy, leading to his embarrassment as he tries to alert the Duke about the supposed threat. Meanwhile, Piero slyly retains the actual bomb for his own sinister purposes.