I grouped with a friend of mine who was farther up the quest chain than I was. I was looking for the Royal Crypt, at lvl 4 of the cathedrel and he was at the Scoundrel. We disbanded and Leah and the Scoundrel stayed behind with me, I could not dismiss them. I continued on through the Cathedrel and completed the objective to find the Royal Crypt, then the Skeleton King's Crypt, and received the quest to escort the Scoundrel, but not to kill the Skeleton King. Once I got to the Skeleton King's crypt, he was not there to fight.