Velvet Assassin

If you are working toward Eagle Eye (all collectibles), you will get this along the way, specifically when you obtain the Army Honor Dagger in mission 3 (Death of the Butcher - Cathedral).

Candied Skull had a fantastic walkthrough, but the site is now down. Instead, here's another one you can follow.

http://wikicheats.gametrailers.com/Velvet_Assassin_-_PC_XB36...