Melai relays a terrible story of an Erudite attack upon his brother. He explains that he can't take vengeance himself as he's watched non-stop, but that I should go talk to the Bowyer Thindel, a friend of his that has vowed to avenge Melai's brother.
Bowyer Thindel sends you to listen in on the Erudites that killed Melai's brother. They apparently meet nearby.
Head to the building across from The Scratching Post. Work from left to right in the broken down rooms until you hear a whispering Erudite talking. You'll overhear them a bit, and the quest will update.