Dishonored

This achievement is stackable with the following achievements*:
^{*Although all of these achievements are stackable, the "Well Mannered" achievement is specific to its respective mission of which this solution does not cover. Please refer to the "Well Mannered" solution if you wish to stack all mentioned achievements.}

If you are playing a Low Chaos playthrough, you will net these achievements easily. If not, you can get these achievements on mission 8, The Loyalists.

SPOILER ALERT! This solution contains spoilers from Dishonored. If you have not reached mission 8, do not continue.

I got this one, along with the "Faceless" achievement very easily after I completed the main campaign, and in just a few minutes. Load up the mission "Lady's Boyle's Last Party" and jump on into the water. Just keep using blink through the water and go all the way down the canal to the other end. Staying underwater will keep you from being noticed by any of the tallboys or guards. Get out and blink over to the party entrance where you can be seen and not have it count against you because it's a masked party. You will hear some lady lose her invite because of the wind. Walk over and grab it so you can attend the party. When inside just talk to everybody and kill time until a guest named "Lord Brisby" shows up - you will hear guests say he's there and wants to talk to you. He gives you the non-lethal option of taking out Lady Boyle (she's the one in black btw) Go over and talk to her and go through some dialogue choices - ask her to show you more of the upstairs, do not clue her in as to what is going on! Follow her upstairs and when you get inside her room get behind her and choke her out. After you do this you will get a waypoint showing you the way to the basement where her loverboy is waiting to take her away. All you have to do is go down a few flights of stairs carrying her without being seen. They way I did it was to clear the way first by using sleep darts on anybody in the stairwell, and carrying their bodies back up to her room so nobody would see them. Save often and if you get seen just re-load and take them out before going down again. After you give her to her boyfriend all you need to do is leave the party and jump back into the water, using blink underwater to get back to the boat. I suck at stealth and I got it so I'm sure you can too!