Mysteriöser Feind

Go to Celestia and ask about the wounded orc.

An hour ago our scouts found a wounded orc near the city wall. They say, he is in a really bad condition. He's delirious and mumbles something all the time. They took him to Celestia, our best healer.
Maybe this is the lead that you're looking for. Go to Celestia and find out what had happened to him.

I'm sorry I couldn't save him...

Church? Well, this makes it easier, right? The representatives of the Trinity Church most probably know him.