Magistrix Carinda at Falcon Watch in Hellfire Peninsula wants you to go to the Pools of Aggonar and retrieve Arelion's Journal.
My husband, Arelion, had been fascinated with the Pools of Aggonar ever since we arrived in Outland. He spent much of his time studying slimes, of all things!
He went missing in there a few days ago. They say he's dead and there's nothing I can do about it.
One thing I can do is try to ensure that his research doesn't die with him. Go northeast to the pools and look for his journal. He always carried it inside a brown knapsack.