In an interview, Eva Green confirms that she has a nude scene while playing Ava Lord in "Sin City: A Dame to Kill For", which premieres in theaters on October 4.
Q. Had you read the comic novel “A dame to kill for” before saying yes to Ava Lord’s role? Ava is the archetype femme fatale and the role seems tailor made for you (although you may don’t like to hear it :-) . Did you have any reservations regarding the “light clothing” as presented in Frank Miller’s novel or you consider it as “just another costume”?
EG: Ah, the nudity… Well, for the character her body is a weapon, a tool she uses to lure men to her, therefore it isn’t gratuitous. Also I trusted Robert Rodriguez’s eye for the way he filmed all the scenes and knew that they would be done tastefully, artfully, and he would put me to my best advantage…
http://evagreenweb.com/2013/05/23/second-exclusive-evagreenweb-com-qa-with-eva-green-part-i/