Employer: Basso [South Quarter / Riverside - The Siren's Rest]
Availability: You get the opportunity to take this mission after you have completed the fourth chapter of the game. You need to meet up with Basso, again, but this time at The Siren's Rest tavern in the South Quarter.
Your destination has been shown in the above screenshot - it is located in the central part of the South Quarter, in [South Quarter / Riverside - Skinmarket]. Before you get there make sure that you have, on you, at least one Rope Arrow, because you will be, otherwise, unable to explore the first one, of the two locations, necessary to complete this mission.
Unfortunately, reaching the apartment that is your primary objective, is much more complicated than it might seem, at first. Start somewhere to the South of the mission objective marked by the game, i.e. somewhere near the underground entrance, which you have used after you completed the second chapter of the campaign mode. Take a look around this location and find the interactive catch , and send a rope arrow there. Do not worry about the fact that you can't reach the rope yet.
Now, you need to reach one of the main streets around the mission objective, on the Northern and Western side. Locate the Western door to the apartment, ABOVE the your destination and enter. Explore the small room and find here a document (South Quarter - Watch Captain's Orders), a Perfume Bottle - 7G and a Pen - 4G.
Approach the window on the right and note the rope that you have extended earlier. Climb onto the window sill and jump towards the rope. You now need to slide down, a bit, which will allow you to get next to the window into the destination (the above screenshot). Jump again to get inside [South Quarter / Riverside - Little Lucy's Room]. Explore this room and collect the Candlestick - 6G, a Knife - 2G, a Fork -2G and a letter (Little Lucy's Last Letter).
You now need to leave this location. So, jump towards the rope again but climb up, this time and enter the room above again. Go West and watch out for the guard there, who may be patrolling the area. The entrance to the next apartment is above the alley, but you can easily climb there. In this location, you can find a Pocket Portrait - 4G, a newspaper (Newspaper - The New Watch Laws and You!), a Pen - 4G and a necklace (Comfort's Necklace - 50G), whose collecting ends this mission.