Rumor has it that old Magus Otto Von Brisbane is holed up in there somewhere but according to the mad mage Doug Douglason he's "never been quite the same since he started eating human flesh". Nonetheless the council of wizards has promised Mindark that if they manage to find him they'll finally teach him how to cast Read Magic.
Here's where they've explored so far:
Hireling Vladimir Putin got his head bitten off by a massive Tarantella Spider in the north tower but otherwise there's been a significant haul from the Sequestrium so far, including a spellbook with Mirror Image and Magic Missile, as well as three scrolls and a magic dagger and some 1500 gold pieces.
Edit: A lucky roll on my Narrative Critical Hit table has resulting in Mindark also acquiring a dagger coated in Tarantella poison, which promises potential entertainment at parties and nightclub fights.
