Sydney Sweeney shows you how Christy is acting out a role she needs to make real for herself, and how she gets in deeper and deeper, until she’s drowning. The movie, fashioned with straightforward skill by director David Michôd ("The King"), starts out as "Girlfight" only to turn into the sports-biopic version of "What’s Love Got to Do with It." It's a wrenching portrait of abuse, enabling, gaslighting, and just how far domestic violence can go.