Reward: 4100 exp
While completing the Crabs versus Skeletons quest, while in the central room, ransack it, in search of a key next to the table, which opens the next door. In the corridor that you follow, you need to watch out for traps on the planks. With appropriate spot, you will be able to notice them. If not, it is best to throw something at them, which detonates them, even if you fail to notice them. The acid cloud can be stopped with nearby crates.
At the very bottom, you will find several exploding zombies that are, additionally, standing in a big puddle of oil. It is a good idea to cast rain over your part and launch something at the, which will make them explode.
Below, you will encounter ghosts of a father and a daughter, where the former is headless. The girl asks you to find her father's head. If you have explored the city thoroughly, you can remember that one of the guys had a talking head.
Return to the city and find the man that entertains the crowds with the talking head. To collect it without any problems, you need to complete the "Warming the Crowd" quest, because everybody will walk over to the other side of the square, then.
Unfortunately, to convince the head that it needs to go with you, you need to defeat it. As soon as you succeed, return to the cave and give the head back to the daughter. This way, the quest will be completed.