Hi fellow assassin,
In case of you wanna know how much time you gonna need for this achievement (if you need it for a challenge or so), I wanna share something. It should take you about 15-20 minutes, since you can skip the cut scenes in the mission.
I got this while doing the "Unseen Assassin" achievement. I followed quite directly this guide:
and the achievement popped at the end for me as well. Make sure to destroy the cameras, pick up a few objects, not getting seen, etc. as shown in the video guide. This grants you enough points at the end to reach the "Mastery Level 5", required here for the achievement.