White Pearl Quest

Name: White Pearl Quest.
Location: Ankrahmun.
Reward: White Pearl.
Monsters: None.

Spoiler:

Being in Ankrahmun, we have to enter the Serpentine Tower. There we go down to the floor with the hearth (one higher than the one with the trapped monsters), put the pot on the fire, and enter the teleport.

The reward is in the chest.