If you're hoping she puts on some fatigues, straps on some semi-automatics, and helps take down that South American dictator ... sorry, but no. According to The Hollywood Reporter, she's playing Mickey Rourke's girlfriend, and probably the only major female role of the film. The girlfriend is a musical lass, and so Murphy will actually perform a musical number at some point in order to break up the testosterone. Perhaps one of the other expendables will fall in love with her in order to remind us that despite hanging in an all-male mercenary unit, they're totally straight. In fact, I'm willing to bet that's precisely what happens.
Singing was what we last saw ... er, heard Murphy doing. You might remember that she was the throaty, popular penguin Elijah Wood had his beady eyes on in Happy Feet. She also has an album to her name titled Faster Pussycat.
So, there you go. A girl in The Expendables who will give them a beautiful memory to carry into the South American jungle along with all their weapons and muscles.