Where is the key to the basement door?

Hint 1 of 14:

Gee, keys are pretty difficult to come by in this game, aren't they?

Hint 2 of 14:

I would imagine that Xaver has them in the drawer of the front desk.

Hint 3 of 14:

Did you ask him about the locked door?

Hint 4 of 14:

He's less cooperative than Gerde.

Hint 5 of 14:

Perhaps you could create a distraction.

Hint 6 of 14:

Did you notice the back door that leads to the alley?

Hint 7 of 14:

If Xaver thought someone was knocking, he might leave his desk long enough
for you to get the key.

Hint 8 of 14:

Do you have anything in your inventory that might create a "knocking" sound?