This quest is mostly identical no matter which side you are on. Volen will advance you 25 Gold; Fiorde won't give anything.
Volen or Firode says your first task is to go to the Abandoned Cave, a two zone cave near the north west gate, which he marks on your map. You need to got there and clear out the Goblins, returning with the Cave Goblin Shaman Staff to prove you've done it.
"I have the Shaman's staff. When I'm ready, I can return to Volen/Fiorde and collect the reward I have coming."
Return to Volen or Fiorde; they take the Cave Goblin Shaman Staff and Volen gives you 25 Gold for each Goblin killed, minus the 25 Gold he advanced you, whilst Fiorde will give you 20 Gold per Goblin killed. Volen promotes you to Squire in the Knights and Fiorde to Protestor in The Righteous.
Your next assignment is undercover work. Volen and Fiorde both give you 50 Gold in advance.
First go to Ophelia's in the Commerce District. Say you need something special, and choose a colour. Ophelia says she needs some Wild Silke Flowers from the beach. Ophelia may need her disposition boosting first.
Get the flowers which are east of the town and north of the port - there are several Mud Crabs nearby - and return. Ophelia tells you to keep the flowers as they are to impress your date.
Change into your new gear and, go to The Thirsty Peasant between dusk and midnight. Take some Beer, or buy some from the barman. Speak to Marvian Grolend and ply him with Beer until he tells you about the Skooma being smuggled in through the Graveyard and Sewers.
"So, The Righteous are smuggling into the Slums through the graveyard and sewers. They can move almost anything they want in or out of the Slums without the Legion or the Knights knowing about it. It certainly helps to explain how they are able to finance their operations. That must be what Volen is looking for. I need to go back and report this. Unfortunately Marvian never told me where in the Slums they exit the sewers. If I knew that also, the information would have been invaluable."
Return to Volen and give him this information. He pays you another 50 Gold, completing the quest.
Change into your new outfit and go to Brend's Barrels. Either take some Beer with you, or buy some from the barman. Talk to Porventia Hylanto, plying her with Beer until she tells you about the smuggling operation being conducted through the Sewers via the Old Silver Mine north of the town.
"So, Varo's Knights are smuggling into the Wealthy Section through the mine and sewers. Just to save on taxes? Only the rich are that cheap. But it should be useful information. Somewhere in the Wealthy Section is a supply of goods that can be stolen, but not reported as stolen. At least not to the Legion. If only Porventia had told me where they exit the sewers, then I would know exactly where the goods are stored. Without knowing that, the information has limited value. But I still think I'll report it."
Return to Fiorde and tell him the new information. He pays you 50 Gold, and this completes the quest.
Your next task will be continue your investigation into the other faction's smuggling operation in A Sewer.