Mass Effect 3
68 Achievements
High Society
Go undercover to follow a lead.
How to unlock the High Society achievement in Mass Effect 3 - Definitive Guide
Just play the level slow and steady and try to avoid detection. Think of it as a James bond themed mission.
Video below showing the entire level and yes it contains spoilers.
During the second mission, you will be in a club. You will be tasked with going undercover while your new companion, Brooks, works behind the scenes. You will be given tasks to do while Brooks, does all the work and in-between these tasks you will have to 'mingle' in the crowd. Eventually, Brooks will get to her destination, whereupon, you will join back up with her, finishing the mission and unlocking the achievement.
Story related, cannot be missed.
Story related. If you want more info, continue reading. Otherwise, know that this will unlock through the natural progression of the story.
After the last trophy, find Liara and talk to her to trigger the next cutscene. You'll be taken to a formal party at the casino. While you're around mingling with the guests and playing games, Brooks will be going through an air shaft to sneak into a panic room. A couple of times, you'll have to do some hacking to help her out. Use your other squadmate to distract the guards so that you're clear to hack away without being seen. If you do get spotted by a guard or a camera, move to the nearest guest or game and interact with them/it. Once you get into the panic room, a cutscene and dialogue options will end the mission.