Seeing the below clip from Michael Winterbottom’s “The Killer Inside Me,” you’d never know that Casey Affleck is playing a deranged sociopath. His lovely sweetheart, Amy Stanton (Kate Hudson), certainly doesn’t. But that’s exactly what Affleck’s quiet, baby-faced lawman Lou Ford is. Really, the less you know the better. If you really must pull away the veil, read Kurt Loder’s glowing review and then check it out in theaters beginning today.