How many scenes have you watched? That quest is a "slow bad end" and so you are meant to unlock all the scenes, then reload a saved game and rescue her as soon as possible. Vehlis can be saved after the 2nd or 3rd scene if you did the right things.Can someone help me out here, I'm currently at the section where you're suppose to buy a potion before rescuing Vehlis, I followed all the step within the guide. However, whenever I come to rescue Vehlis, it fail the mission even though I have the potion.