The ancient Crystal Keep of Cyre resides deep within the Mournland, standing tall and abandoned. Chunks of the tower remain missing from a decade of decay and thieves thinking to make light with the valuables inside. Hundreds of Creation Patterns remain deep in the bowels of the building. The tower, unbeknownst to these thieves and brigands, actually requires a distinct imprint to open the locks that bar the door. A small crystal, possessed by any self respecting Psion, will mould itself into the lock and swing wide the doors.
This is why your group has been hired. Psionic experts, powerful psionic warriors, delvers of the deep- you have earned your reputation as Tomb Divers of a very particular kind. So your employer, an unknown Mr X, has offered a substantial sum of money to enter into the tower and recover a very specific creation pattern. A bank credit, only valid in a months time and only in the presence of the signatory, has been given to you. You have since taken the credit to the largest financial operator in Sharn whom has identified the credit through mundane and magical means- it is real. 10,000GP will be paid to you upon completion of the task.
You have also been given a "gift" up front from the mysterious benefactor, enough wealth to equip your party for any dangers you might face- and the freedom to keep it when the job is done.
You have contacted your old party, you have reminisced already, you have drunk yourselves stupid on some misspent gold from Mr X's purse and are now camped about half a days ride from the Crystal Keep.