Three years after the loss of their son, retired sheriff George Blackledge (Kevin Costner) and his wife Margaret (Diane Lane) attend the wedding of their former daughter-in-law Lorna (Kayli Carter), who marries Donnie Weboy (Will Brittain) and takes her son Jimmy to live with him in town. On a trip into town, Margaret is shocked when she witnesses Donnie hitting both Jimmy and Lorna, right out in the street. She decides to bake a cake and pay them a visit, only to find they've left town with no forwarding address.

Margaret convinces George to leave their Montana ranch to find out where Lorna and Jimmy have gone, in order to rescue the boy. They discover that the Weboys are in the Dakotas, but they just as quickly realize Donnie's family is a dangerous one, with a reputation for violence that is overlooked by the law. George and Margaret try to convince Lorna to come with them, but the young woman fears his mother (Lesley Manville) and her sons will kill her if she tries to leave. The Blackledges find their quest proves more difficult and deadly than they could have anticipated.