Jessica Chastain, Michael Greyeyes, Ciaran Hinds and Oscar winner Sam Rockwell star in this A24 (shorthand for GOOD FILM) culture clash/fish-out-of-water story of a painter, Catherine Weldon, who ventured West to capture the last great chiefs of the plains before they were all gone. “Woman Walks Ahead” was directed by British TV mainstay Susanna White (“Bleak House”) and opens June 29.