I just watched the departed,and this idea came to me. The FBI would be after a high level mobster, or arms dealer even, and need someone to get close, only anyone who does gets killed. I would be a new female agent assigned to gain his trust and get close to him. i would be 'fired' from the bureau for something beleivable and gain employment at a strip club that he frequents, where I would appear to be his dream girl.
I would be taken in by him, become his very own fantasy girl. It would be a long assignment, and perhaps even marry my target when he asks. All the while, I would be gathering intel, reporting said intel when I could to my handlers.
For this, I would need someone to play the mobster/arms dealer, depending on works best.