Other than all the rats you should be able to do this quest fairly low level.
STEP 1:
(Medieval) The Alhambra
Go to the room "An Abandoned Passageway" (this room should contain a rat's nest) and is located under the Governor's office.
Kill the Rats
Open Nest (Kill more rats)
get all nest - you should get a Medical Book
STEP 2:
(Medieval) Saint Dennis Abbey
Find the Physician
Ask Physiican Book
Give Physician Book
STEP 3:
Profit!