While in the Royal Museum level, go through a door with a pyramid picture next to it. When you see a huge pyramid, go around it until you see a door. Go in the door. Lepelt will be standing behind a pot. Do not go over there yet. Instead, Jump into the sarcophagus that he planned for a trap and let the puppy trap him. Once the puppy traps him, jump on top of the sarcophagus and go where the face is. He will say a couple different things each time you jump on him.