At the red square of carpet with two candles use the levitation spell to see the secret room. Towers II Hints by Vince Valenti and Jag Jaeger 1.
Custodians have the responsibility of cleaning up all of the rooms in the tower.
Try talking to them about keys. In the throne room, behind the gold doors, is a locked secret door. No key will unlock that door, but there is something in that very same room that will. One of the thieves gives you a hint on which chain to pull first. You know what chain to pull last by looking at the punctuation of the phrase on the scroll.