Nether-Stalker Mah'duun wants you to dismantle 5 Arcatraz Sentinels. Return to him in Shattrath's Lower City once that has been accomplished in order to collect the bounty.
The sentinels within the Arcatraz have gone haywire. The prisoners run rampant and the guards attack those that would help.
Mah'duun hears the speaker on the nether winds. The speaker says to destroy the sentinels.
Accomplish this and today's bounty is yours.