Two guards make the rounds here in the basement. Guide:Keepers Chapel/Thief - The Dark Project/Escape! Walkthrough
Loot the shelves and chests before you open the hidden door at the end of the hall.
Search the grass between the hedges until you find it. A secret panel hides a way into the keep's basement. Find the wooden door at the top of the ramp. You cannot yet enter the Air Tower the towers have special locks and require special keys to open. Take any keys, potions, and loot you find on your victims. The hedges, walls, and lack of light make the tower courtyards ideal places to eliminate the guards and mages pacing through. There are doors on either side of the main gate's courtyard. Just inside the keep walls, the front door is cheerfully lit. Find the secret exit through the sewers beneath the keep and escape. Kill no one and leave the mages short a good 1, in loot.
Burringden and certainly needs it less than you. Seek out the quarters of Regalio, captain of the guard. Locate a pair of jeweled reading glasses and liberate them from the mages. Each of these outer towers house the mages of one of the four elements, while the Central Tower is home to the great central library, guards, dining, and living quarters. You begin at a castle with a Central Tower surrounded by four towers. Mages are tough customers fighting them would be a mistake. The mages of Earth, Air, Fire, and Water possess it. You're after the Talisman of Earth this time.