Beholder

One very easily missable achievement.

First, you need Christopher and Gertrude Danson to move in to your apartments.

Peep on them often until you see the dude beating up his wife.

Talk to both of them and use 500 reputations for Chris can tell you about his troubles.

Sneak into their apartment and find a letter from his dad.

Confront Chris using 500 rep about his father, this next part is important.

Threaten him to help you and then wait until they leave the apartments.

Call the Center and tell them you are ready to go, there you go, achievement unlocked!