This quest is not available in game.
Kill Huntsman Radley and Cavalier Durgen before returning to Kirsta Deepshadow in Western Plaguelands.
My real mission was to weaken the Scarlet Crusade's outlying forces and then infiltrate Hearthglen to gauge their numbers. I'm still in no shape to do it on my own, so perhaps I could ask you to aid me again, <name>? From what information I gathered before being discovered, the Crusade has two important members that are the backbone of their forces outside the town: Huntsman Radley and Cavalier Durgen. Kill them, and we're making progress. They should be along Hearthglen Pass outside the town proper.