File R-07
You will need to let the guards at the fence see you so it turns to caution but not alert. They will follow you for a short distance. Then when they turn around go up behind them and stealth kill them.
Break through the fence and sprint around the left up the boxes and then up the stairs into the building, then carry on around the left of the building. Stealth kill the two enemies at the furthest end of the building.
Slice open the fence and go outside, let on of the guards on the right see you and follow you, when he turns around stealth kill him. Climb the boxes on the left and stealth kill the guy the finally stealth kill the last guy.
You can reload checkpoint if you get detected.
Achievement unlocks at the end of the chapter.