After entering Tierville, you will happen upon the same guards you met in the beginning of the chapter. If you answered as described, the officer in charge, Integrity, will have a job for you. You have to find two pieces of evidence of a smuggling operation going on in Tierville. Once you get your hands on Smuggling, you can run back and finish this before continuing.
Part 1/2: Is found marked on the map right here in Tierville. In a room with two smugglers.
Part 2/2: You have to go back to Shadowlair: The Slums (North Neighbourhood) for this one, but it is also marked on your map.