The Torn Letter's Response is found inside a "Dusty Leather" satchel within the Caverns of Araneae near Wortham and Wortham Bluffs, accessible via the ferry at New Tristram in the first act of Diablo III. It is only found after Torn Letter.
It reads as follows:
- With great pain, I must admit that our king is no longer able to separate reason from madness. He orders the caverns to be filled with the archbishop's monstrous creations and will hear nothing else. Perhaps the legendary ancients themselves once dwelled there... but now we must desecrate their ruins.