Baroness Anastar holds him? Here in the Plaguewood?
The Plaguewood is a big place... but we will find him. We WILL find Gidwin.
Immediately to our east and our west are a pair of necropoli that flank the entrance to Stratholme. Inside them, you will find a pair of death knights - Rivendare's lieutenants. I doubt either would have any use for a paladin hostage, but perhaps they will have some information on his location.