You automatically receive this quest after telling the Town Guard about Keltar's death.
If you’ve been activating portals as you travel, you’ll probably find it quicker and easier to make your way to the nearby Teardrop Hamlet portal and use that to get back to Thylysium. Once in Thylysium head South to the army camp, in the South of which you will find the Paymaster.
Talk to the paymaster for your reward and the end of this chain quest.
It's true... smaller towns don't have their own treasury. That's why several villages and small towns have joined forces. Regions that don't have treasuries to pay off bounty hunters are being overrun by criminals. I'm glad that we have one. Here's your reward.