Volume 2, Chapter 2
The "nerd" is Chip, and he's the one tasking you with optional objectives to find cameras and such. You will get this achievement by first getting 3 others:
1) Find all the cameras in the train station (before going up the elevator) to get:
2) Once you are upstairs in the train station, directly across from the elevator as you enter is a control panel to examine.
3) Around the corner in the next room (with a couple of security guards and a TV) is a motion detector. It's on the same wall as the text that tells you to change camera angles with the right stick.
Once all 3 of these Chip-related tasks are done, this achievement should pop. Should come naturally if you're examining everything you can. As per the comments, it appears this needs to be done all in one go, without restarts (or crashes).