Sacred Haven of Debauchery

So, guys, I need help with the second part of the game. Basically, I approach the Sphinx (which asks riddles), and it replies to me: "I will not ask you a riddle. I will reveal a secret to you. I serve the dark forces, and you have wasted your time." Something like this happens: I don't know what to answer! But I need to answer, because according to the scenario, I need to do it. The map is called "Riddles".