The Moaning Lands of the Dead and Dying. Many foul creatures of undeath roam here and seek living flesh, no one is quite sure what happened to this large desert island. Maybe you could unlock the mystery and free the tormented.
The PCs find a strange helmet, when donned it will take control of that PC and speak and act trough him/her. It explains that it is benevolent and needs their help in a quest and that it will stop possessing the PC when the task is done. Great if a player is gone for a number of sessions.