The Vault of Eleven Locks

“The eleventh lock opens with a sound like a chest full of coins dropping from a height, and the door -- two feet of engineered iron -- swings inward on bearings that have not moved since before anyone in this city was born. The air that comes out is cold and flat and smells of old paper and something sharper underneath, like phosphor or old magic or both. Somewhere ahead, stone grinds against stone in a slow deliberate rhythm, and the sound is either a mechanism running or something very large shifting its weight. The Compact's broker told you the vault had no internal security. The broker also told you no one else had the combination. The fresh torch marks on the archway suggest the broker was wrong on both counts.”