Pregnant Reese Witherspoon arrived on the set of her latest film, Devil's Knot, yesterday in Atlanta. Sporting a retro hairstyle and polka-dot dress, Reese looked ready to get to work in front of the cameras. The film is based on the story of the West Memphis Three, a group of teens convicted in the 1990s of murdering three 8-year-old boys. Reese is just one of the major stars attached to the project. Fellow Oscar winner Colin Firth shares top billing with Reese, and True Blood's Stephen Moyer just signed on to the Devil's Knot cast. Stephen and Reese are both expanding their families later this year, as he and wife Anna Paquin announced they're expecting twins.