NPC in town named Ornad Saidor first offers the quest "Hexmaster Jorni"
"Two weeks ago Jorni, a wizard student here in Arinox, fled town because of the accusations against him. They say he was conducting horrible experiments on living beings - as the ancient Hexmasters were doing. I don't know if what they say is true, but I heard the magistrate is looking to question him. Late last night I think I saw Jorni on the streets, entering the catacombs in the northern part of the town. I know someone who will pay a good price to find out the location of Jorni. Would you be interested in helping me?"
Quest description will say: "Explore the catacombs underneath the town of Arinox and report back any trace of Jorni to Ornad Saidor."
The first level of the catabomb will hold no monsters, simply a maze with lots of tunnels. In one area of the tunnel there will be a locked door. Standing near that door will be enough for the quest to update. Further a window will open telling that there is a torn piece of a novice robe caught in the door. When the player reports back to Ornad Saidor, the following dialog takes place:
OS: "You found a sign of Jorni? So you are willing to work for me?"
P: "I am. But I need help to continue."
OS: "I will tell you all I know about what has happened. About a year ago some townspeople started diappearing. One every few month so people were worried, a murderer was in town, but all investigations lead to dead ends. Then last week another one disappeared - the daughter of a wealthy trader in town. He hired me to find the murderer and bring him to justice. The night before yesterday her body ran around town - horribly twisted and without a head, but still walking. The townspeople were enraged and some openly talked of tearing down the mages guild when the guildmaster stopped them and said internal inspections had found the responsible. The novice Jorni who came to the guild a few weeks before the first murder. All evidence was against him since some personal items of the daughter were found in his rooms and he even came from a town in the far north that is very close to a former stronghold of the hexmasters of old before they where extinguished by the holy church in the cleaning crusade. The townspeople wanted to execute him right away, but this is a lawful town and he was imprisoned to be judged in the morning. During night some townspeople wanted to kill him in prison but somehow he escaped in the tumult and ran to the dungeons beneath the city. Even though that seems to confirm his guilt he must have his labratories there so no one dared to enter the dungeons, yet. The mages guild is probably willing to help, but they say they need to wait for a high protector from the church to shield them during the operation. My master doesn't want to wait that long and I for myself find the quick investigations of the guild somewhat suspicious. However, to continue into the dungeons you will probably need the help of some mages since what you describe sounds very much like a magical lock. Since Jorni seems to have been an outsider in the guild it shouldn't be hard to find someone among them who will help you break the lock."
A small group of novices are the only mages the player will see and surprisingly they turn out to be quite friendly towards Jorni.
P: "I have been commisioned to find the novice Jorni who seems to have hidden in the catacombs behind a magically locked door. Will you help me break the lock so I can further investigate his actions?"
NM: "Whatever you might have heard, I can't believe he is a hexmaster. The daughter and Jorni were in love with each other. That's why he had personal items of her. I understand that the guild leaders were pressed to name someone given the hatred of the townspeople, but it was wrong. Jorni was distant the last weeks and even told us - his only friends - just that he had a very bad suspicion and was looking for proof. I can't believe he is a hexmaster, but that he is a victim. We will help you to open the lock, but can't do more since we have orders from the guild leaders to stay away from the catacombs so even that little help might have dire consequences for us. Show us the door and we will break it."
When the player goes to the door again the three mages will appear again and show some text will show: "The door is open now. But that magic is more than Jorni could master alone unless he really was a hexmaster. I fear he is in great danger on his own. Can't really believe he fled to the dungeons instead of the woods when he managed to escape this night. I hope you find him and pray that we were right and he is not really the hexmaster. I am sorry that is all we can do."
Then the novices vanish again, but the door is a stairway now to deeper levels.
After catacombs with some moderately heavy monsters (skeletons) finally there is a room that shows a text on enter. "Some monsters are bashing against the door at the far end of the room. It is obvious that it will not stand much longer. Unfortunately the monsters seem to have seen you and start advancing against you."
After a heavy fight against a group of two medium heavy and one heavy skeleton the player finally enters the room at the end. There he finds Jorni who tells the following story:
Still need to write this. Will come tomorrow
After that we can keep going on that line. Perhaps we will be given a key which unlocks the door and a new quest to bring back Jorni's Journals or perhaps Jorni dead or alive. Something like that. We could also keep working on the story to explain why Jorni became a hexmaster.
Ornad Saidor is no agent of the mages guild, but of an important townsman who lost his daughter to the experiments and tries to hire help his revenge. When you get inside the dungeon Jorni might already be dead, but by questioning the right people you find out about the plot, have to turn it against the real hexmaster and finally have to fight the hexmaster in the catacombs. Afterwards there still is an even more dangerous monster somewhere around the town, but that might be part of a later quest and you might not even find that out yet (only perhaps get a very little hint) since Jorni had no idea what really going on. Some later quest where people don't return from visits in a remote city might uncover the rest.
Alternatively, Jorni really is a hexmaster, but only a weak one. A lot of chaos in the world might come from a coven of hexmasters with a secret hidden goal they want to reach at any cost.