Head on forward and take the elevator up in front of you. Once there start on over to the left and take the stairs there upwards. From there it is a simple matter of fighting your way on through a horde of Skeletons, mages, knights and the occasional dragon.
Make it to the blue portal on the ground then step into it to come to face the Handsome Sorcerer. He will take a total of 3 forms: Handsome Sorcerer, Necrotic Sorcerer and Demonic Sorcerer. Each has their own unique attacks and summons. It involves a lot of careful work. The good news is if you die, he will stay in his present form, though it will be fully healed. After that you are onto the final objective for the story line: Free the Queen