Leaving Thebes, the party heads on their way to Delphi. The only obstacle in their path being the Sons of Atlas' activities mining Mt. Parnassus with the Athenian Prisoners of war they have. The hidden door to the Underworld that Orpheus created is said to be somewhere inside, but hasn't been unlocked just yet. One thing to be understood about D&D: never underestimate the ingenuity of players.