As commanded, I locked the trap door that leads to the chambers below. If you need to go down there, I hid the key in a backpack and stuck it in the north tower. Remember, the veil will affect you, just as it will Ravenwatch. So if you find yourself in the chambers below, be careful. The veil may be a shadow, but it hides very real dangers!
And don't leave this note lying around. If I wanted anyone to see it, I wouldn't have hidden the key in the first place.