The PCs are looking to gain entry to the Glantri School of Magic, after the initial admission tests they are drawn into a commotion where one of the other students is being attacked by an evil sorceress. He tries to flee but but is killed, and the PCs are framed for the murder. The authorities are called and bribed to just kill the PCs, they flee and are chased and taunted by the evil sorceress. Eventually, during one of her attacks, she opens a weak spot in the ground and the heroes are dropped into the warrens under the school. They must navigate the warrens, which are shrouded in magical darkness, defend against further attacks, and find escape where they can prove their innocence.