A middle-aged snob (Imelda Staunton) discovers that her husband has been carrying on with her best friend for years, moves out of her McMansion and in with her estranged and decidedly less priggish sister (Celia Imrie). After a spate of strained, fish-out-of-water situations, sister takes her to a community dance class, where she, with superhuman predictability, finds new confidence, yada yada. I know there’s a dearth of movies aimed at our older folks, but would the teeniest surprise be too much to ask? Grossly overqualified cast includes Timothy Spall, Joanna Lumley and David Hayman. (111 min, Aug 25)