There are numerous mysteries and puzzles to unravel in Indiana Jones and the Great Circle, with many woven across the streets of the Vatican City. 'Signs of Trouble' is one such mystery that could put your puzzle-solving skills to the test, as it's not only a tricky mystery to trigger but involves opening a seemingly impenetrable safe at the Vatican City Excavation Site. Knowing how to open the Excavation Site safe might also baffle you if you stumble across it before triggering the mystery, as there's no way to open it nearby.