There is a water symbol in the desk. Your father used to have this office. Some other thing else also belonged to your father.
What thing?
The divining rod! Wenzel left it to his basement. This must work as a key.
What to do with the rod?
Use the divining rod to the water symbol in the Mayor's office and behold, a secret compartment!
What else should I do?
There are more secrets if you just find them. Use your globe.. I mean head!
My globe?
There is a secret compartment in the globe, too. How neat. And you get a glass!
What about the keyhole?
Yes, use the key you got from the first secret compartment to the keyhole in the second secret compartment to
open the third secret compartment (huh!).
Booze!
Have a drink! You deserve it. Don't be a barbarian, use a glass.
Buy me a coffee