The Vanishing ending explained (spoilers)

[clayton]

Jeff (Kiefer Sutherland) goes with Barney (Jeff Bridges) to his cabin. Barney persuades Jeff to drink drugged coffee in order to find out what happened to Diane. Jeff passes out and Barney buries him in a wooden box. Rita (Nancy Travis) finds out from Jeff's neighbor, who overheard them arguing, where Jeff and Barney went and Barney's car license plate number. She finds Barney's address by going to the DMV and saying that her car was stolen. Rita goes to Barney's house and talks with his daughter and she tells him how to get to the cabin. Rita reaches Barney's cabin and bluffs that she has kidnapped his daughter. Barney believes her and Rita gets Barney to drink the drugged coffee. He passes out, buying Rita some time to find Jeff. She notices Barney's muddy shoes and a nearby shovel and figures out he buried Jeff. She rescues Jeff but Barney is now awake and attacks her. A revived Jeff kills Barney with the shovel. Jeff now realises that Diane (Sandra Bullock) has been dead all this time. Jeff and Rita stay together and vow never to drink coffee again.