In a small inn (the more remote the better), a man turns up dead. There are no wounds on his body what-so-ever, and he aboslutely reeks of garlic.
The man died of a curse that forced him to eat a clove of garlic a day or suffer the penalty. This gets really interesting if the body somehow appears on top of a someone the villagers are suspcious of.
Carnival revelers wear masks and concealing clothes. (Wearing of masks in Venice was first documented in the late 1200s) It allows for the social classes to mix, easing social tensions.