LOS ANGELES, California (X17online) - Angelina Jolie has begun work on her latest movie the spy-thriller "Salt."

"She's a character you never know," producer Lorenzo di Bonaventura tells USA Today. "People who think they know the real her may or may not. Those who think they can tell whether she's in a disguise also may or may not."

In the first pictures from the set, Jolie is seen in various wigs and other disguises.

Adds di Bonaventura, "You're supposed to be kept guessing. She tells you her agenda, but are you supposed to believe it?"

"Salt" has taken an unusual road to the big screen. Tom Cruise was originally eyed for the role, but he dropped out last summer.

The script was changed to make the lead character female, a process the producer calls "complex."

"We had to rethink the whole notion of how a man vs. a woman operates in the business world, in personal relationship and in friendships," di Bonaventura says.

"Salt" is expected to hit theaters in 2010.

CLICK HERE TO SEE THE FIRST PICS OF ANGELINA IN "SALT."