Slaver Brona in Big Bend (at the Torch of Ogguk) asks you to speak to Bartender Icebrew in the Scale Yard about a slave shipment.
Bartender Icebrew can be found in the far northern part of the zone, in a pub. Hail him and tell him that Brona sent you.
You will then be asked to return to Slaver Brona in Big Bend to complete the quest. The reward is some coin and a small amount of experience.