After the cop car chase and carnage, Jim and Grace decide to trek on foot into the open plains and stumble upon a truck-stop town where they break into a motel room. They shower to wash off the blood and dirt, and then as Grace falls asleep watching 'The Birds', Jim goes to call for help.
Grace wakes up next to Ryder. They fight and Grace manages to make it to the bathroom. When it's all quiet she re-emerges with the gun - but Ryder is nowhere to be seen. She walks outside and into the middle of the motel lot. The receptionist sees the gun and calls the cops.
Grace walks towards a truck in gear - and finds Jim, in chains, stretched out between two cabs. Ryder summons her to sit in the front seat next to him - and asks that she kill him, but also warns her that if he releases his foot, the truck will move and kill Jim. Grace hesitates.
The cops show up and shout for Grace to drop the gun. She obliges. Ryder is angry and moves the truck forward and Jim is graphically torn in half.
Cut to the police station where Grace is understandably traumatised. She learns that the mysterious hitcher stole the John Ryder identity from another of his victims and no one knows who he is -- and to make the movie make sense "why"? Nevermind. For some reason, Grace and Lt. Esteridge must accompany Ryder to a new station. In the armored car, Ryder dislocates his thumb to ease off his chains and murders the guard watching him - then takes his gun to kill the two in the front. The van flips over, and catches an oncoming 4x4 which slams into the side of the police car carrying Grace, trapping Esteridge.
Grace is sick of this so she grabs Esteridge's gun and goes to kill Ryder. She unlocks the back of the van, where Ryder easily snatches the gun off her and traps her inside - and then sets alight the petrol tank. Grace manages to get a shotgun from the front and then ducks as fire rips through the van.
Ryder kills the cop, but then Grace emerges from the fire. Ryder casually walks away, deciding now not to kill her, but Grace shoots him in the back - then in the chest -- and as he lies on the ground through the head.