Dawn of the Old Gods: Tyranny of Dragons
The origins of the elven sisters who once lived in the Mornhaven Towers is lost to history. They were said to be powerful wizards who actively fought for the cause of good. All that remains of them now are their towers and some lingering dweomers. The sisters abandoned their homes shortly after imprisoning a demon that was ravaging the Sword Coast. To cage it, they built an underground warding chamber, and then sealed the tower. They then attempted to sink the towers beneath the ground and seal them in stone so that on one could never release the demon.
The party eventually found out that the “Demon” that the elven sisters were trying to contain was actually an egotistical Djinn. The party released the Djinn into the world in exchange for information