Washed-up archaeologist Rip Digman, trying to dig out of obscurity and redeem himself, recruits a sidekick to help him find the lost hat of Hammurabi, an ancient king of Babylon.
Rip, Saltine, and Swooper travel to Venice to look for a historical batch of confetti, but find themselves embroiled in a mystery involving secret organizations, curses, gondoliers, and the knife Brutus used to kill Caesar.