A fascinating and genuinely important period in American history is underserved here by an inelegant structure and unwieldy running time. Matthew McConaughey stars as Confederate deserter turned folk hero Newton Knight, who leads an army of runaway slaves, disillusioned fighters and women against a local government skewed firmly in favour of the landowners. Gugu Mbatha-Raw is the former slave who becomes his common-law wife. There’s a languid quality to much of the film, which flows slower than the waters in the bayou where Knight and his army hide out. It also offers further evidence that Hollywood is happiest tackling racial politics when there is a white man at the heart of the story.