Rewards: Pounds: 1000 (+150), EXP: 450 (+150), Extra: Belt - Iron Scale Belt
Challenges: 1. Do not kill any guards in the Sinopean Club (only counts after entering). 2. Avoid all of the snipers shots.
Hop off the building you're currently on and approach the Sinopean Club in the distance. Don't take the main entrance. Instead, move slightly to the left and climb the building. Look down and scan the area to spot various guards down below, plus a haystack allowing for a leap of faith. When one of the guards is standing close while the other is looking away, perform the leap of faith and immediately pull the nearby guard into the stack (assassinating him). Then whistle so an other comes along, and assassinate him too. If you can manage to quietly kill the third one too, all the better. These kills don't count for the challenge, which only starts when the meeting begins (as you reach the waypoint).
When you activate the waypoint, the meeting begins (and so does the challenges). If a (new) guard somehow manages to see you, circle around the area and avoid any direct confrontation. When the meeting is finished, follow the spy and tackle him. Unfortunately he's shot by a sniper. Quickly move towards the sniper and avoid all of her shots. Fight her at the end of the rooftops to finish the mission.