Batman: Return to Arkham - Arkham City

This achievement is story-related and cannot be missed.

You will get this after your first predator sequence in the game. Just follow the clues to the church and escape the trap by using a smoke grenade. this sequence should be no problem to you since it is the tutorial to the predator sequences in the game.

(the church sequence will start around minute 8)
(video credit: JayShockblast)

Hope this helps you guys!
Any improvements? Please let me know in the comments below !

I struggle with this achievement, I tried in 3 different saves and not pop
I finally made it pop on my 4th try but I did something different:

Once I counter Harley Quinn I did EXACTLY what the game ask you to do
Let me explain
I drop the smoke bomb, then press for the scanner, at this point what I usually did was trying to take out all the thugs as fast as I can but you should take your time!
BEFORE taking out any thug you HAVE to use the detective mode so Batman can talk and listen because you have to take them out as Batman wants you to do it
The thug that you should do a takedown from above, I always made the mistake that first I drop down and then take him down! That's wrong! You HAVE to do the takedown from ABOVE and remember to use detective mode before hand

Now the achievement should pop once you clear the room