This is a long one, so I'll use the guide of Minxy on Steam that I followed to get the achievement myself:
The first part of the As A Mouse achievement starts in the basement. The aim is to get the secret code when you interrogate Abel, then use the code later on at the raider camp. To get the code from Abel you need to choose certain dialogue options, I'm sure there are different combinations but these are the ones that worked for me:
> [Slap him]
> [Let Abel drink]
> "They've abandoned you."
> "Fuck your war."
> [Let him smoke]
> "I hope so."
> [Let him sweat]
> "You'll know soon enough."
Now you'll have the password "Rockingham", you'll have to use it in Act 3, it'll be listed in the guide so don't worry!
At the very start of act 3 we get to finally use the code we got from Abel! Make sure you choose the option "Rockingham."The steam guide by Minxy:
https://steamcommunity.com/sharedfiles/filedetails/?id=20857...