Femme Fatale is actually a moralistic tale about the choices one makes in life. Here, the consequences of two actions by the primary protagonist are presented, and the "good choice" is shown last, where it results in a happy Hollywood ending.
The film ostensibly features Antonio Banderas, but the real focus is on the character played by Rebecca Romijn-Stamos, Laure Ash, who could succinctly be described as an opportunist. In the film, Laure is presented with two choices when she is mistaken for someone else who looks exactly like her while on the run from thugs she has double-crossed. The other person, Lily, has just lost her husband and is contemplating suicide. Laure has the choice of allowing the person to go through with it (and taking over Lily's life) or prevent her from doing so and thus risk her own life in the process.
The movie traces through in detail the consequences of each of the choices. The first time around, Laure allows Lily to kill herself, which leads to her eventually becoming the wife of the future U.S. ambassador to France, who eventually is photographed by Nicolas Bardo (Banderas), which results in the thugs she double-crossed exacting revenge from her. The second time around, she follows a more "decent" path which results in the thugs being killed before they can get her.
I do believe in the tenets espoused by the film: though I don't necessarily believe in the notion of karma, I believe that it's better to live your life in a "do unto others" manner (realising completely that it's pure chance whether it comes back or not). Still, I think it's more satisfying to see that what someone sows is what they reap, as Femme Fatale illustrates.