One of the features of the city of Hax most beloved by adventurers is the anacaleon—a type of enchanted structure to which an adventurer may make a payment in advance and then, on the occasion of the adventurer's death, they will be restored to life and health at the anacaleon's location, in most cases with the possessions they had on them at the time. One nefarious enchanter, however, has found a way to place an additional enchantment on a certain anacaleon: it will bring its "customers" back to life, yes, but then if no witnesses are present it will turn them into stone statues, which it will then transport to their enchanter's location where he can loot them at leisure.
An ally of the PCs dies, but the PCs know that they made a payment to an anacaleon before their demise, so they should be back soon. When they don't return, however, if the PCs try to look into their fate they may discover the enchanter's villainous plan—but to stop it they'll have to confront the powerful enchanter himself.