Spoiler.
You mean the second level in Turkey, the part where you must not show yourself and start playing from a balcony. Go down, walk behind the first and suffocated him. You are hiding behind the large fountain, hanging on the side ,then approach the man leaning against the fountain and suffocated him. Wait untill there is no light near you, go left towards the dark area of the garden and go choking the other two men. Compared to the latter two, go ahead and right, climb the small stairs(dark area), hide behind the little wall, and prepared to jump down when the fifth man do not tip against the light, suffocate him and hide. Now back to the fountain, paying attention to light, until your friend sees you and follows you. Go up the main staircase, you first, and then strike the sixth man on the right (but not immediately, wait a second in front of him and then hit him), your friend will do the same to the one on the left. And then the game is done, and climb on the roof. I tried more than 7-8 times the first playthrough.