A SALT AND BATTERY: I wanted to follow up on our discussion of Angelina Jolie's presence and how it affects whether you'll see a movie with a (spoiler-free) discussion of Salt. As you can tell from the trailers and ads, crucial to Salt working at all is at least some sense of doubt as to where Salt's loyalties lie--if the actress reads too pure or too villainous, we know the answer to the movie's central question early on. Jolie is unique among female stars in that she can carry this off--can you buy uncertain loyalties of someone like a Jennifer Garner, Cameron Diaz, or Drew Barrymore? (Scarlett Johansson might be able to sell it.)
Of course, much ink has been spilled over how Jolie took over the lead in Salt when Tom Cruise turned it down, but I haven't seen anyone really talk about how Salt and Knight and Day are really mirror images of one another. Both depend, to a large extent, on our uncertainty about how we feel about the leading performers off-screen to inform our judgment of their on-screen characters. Is Roy Miller a brilliant secret agent forced to go rogue by circumstances beyond his control, or a guy who's experienced a violent break with reality? Is Salt loyal or a Russian spy? We can't answer those questions up front because of our feelings about the leads. Neither film entirely works, and the two films take dramatically different directions from that premise (one goes for a more comic direction and the other takes things all-too-seriously), but to the extent they work, they do so because of our mistrust of the leading performer, and that's a rarity indeed.