During the early stages of Indiana Jones' latest investigations, you'll come across The Serpent Puzzle under the Pope's Secret Chamber. Water Serpent FountainThere are also the Water Serpent Blueprints to the right of the puzzle, on top of some rubble. Serpent Puzzle Grate 3Take the Serpent Wench back to the hole east of the waterfall. Serpent Puzzle Grate 4To unlock the fourth grate, simply turn the Serpent Wench one more time in the same spot. Back in the Serpent Puzzle room, use your whip to jump to the opposite section of the serpent statue.