Terror of the Crypt
The Town Drunk of Mileth Tavern has heard a man screaming about terrors from the Mileth Crypt and he would like you to investigate.
First, start the quest by speaking the Mileth Town Drunk and asking about rumours. He will tell you about a man who was screaming about terrors and carving something into the stool of the bar. If you walk near the stool on the far-left end of the bar (tucked between the another stool and the wall) and click on it, you will find a carving that directs you to a specific location in Mileth Crypt.
You will need to head to Mileth Crypt 3-1 (1, 1). You may wish to bring help if you're low level. When you step onto the correct location, you will fall through a trap door and land in Mileth Crypt Storage. Slay the Mileth Crypt Terror attacking the Mileth Citizen and you will be given the option to teleport back to the Mileth Tavern. Speak with the Town Drunk again to finish the quest.