|It's late at night and a couple are driving along a road at night, completely lost. David insists they are on highway 99 until they pass a sign that says highway 41. Molly is upset - it's their anniversary and they're spending the night in the car. Suddenly, they see a man in the middle of the road. Molly tries to avoid him, but hits him and crashes the car. She wakes up in the wrecked car with no sign of David. She sees a house nearby and knocks on the door to try and get help. She enters the house and finds the man she hit standing there - only he's dead and starts chasing her.
Stumbling to the main road, she flags down a passing car in a panic looking for some help - it's Dean and Sam in the Impala. She explains what happened and the boys agree to take her back to her car. They get there, but there is no sign of either the car or David. While Molly looks around, Sam says to Dean that they need to get out of there - Greeley could turn up any minute. Dean wonders what they are going to tell Molly. Sam suggests the truth.
They convince Molly to leave the area, heading towards a nearby town. Molly tells them a little more about the accident. She and David were supposed to be in Lake Tahoe - it was their 5th anniversary. Sam promises that they will find out what happened to David. The radio in the Impala suddenly changes to "House of the Rising Sun", which Molly recalls was playing when they crashed. A voice can be heard over the song saying "She's mine". Suddenly, they see a figure in the middle of the road - it's the same man that Molly hit. They drive straight through him, revealing that he was simply a ghost.
The Impala stops on the side of the road and wont restart. When the boys start pulling out a load of weapons from the trunk, Molly gets scared. Dean reveals that they didn't just find her by accident - they were out there hunting ghosts. Sam explains the ghost is called Jonah Greeley. He died 15 years earlier on that same highway. Each year, on the anniversary of his death he haunts the road. Molly cant believe what has happened and wants to leave, but the boys tell her that Greeley wont let her leave the highway. They promise to help her, but first she needs to help them.
She takes them to the cabin where she saw Greeley, so they can look for the corpse. After his death, Greeley's wife took the body and buried it somewhere on their land, but they have no idea exactly where. Exploring the woods, Molly hears a voice asking for help - she thinks it is David and follows it, but walks into the ghostly arms of Greeley. Dean blasts him with rocksalt and he dissipates, releasing her. They continue searching, finally coming across Greeley's house. There are no headstones around to indicate an obvious grave, so they look around the house.
Molly finds an old scrapbook of Greeley and his wife, showing how much they loved each other. She cant understand how someone so happy could turn into such an evil killer. Sam spends some time explaining to her what happens when someone dies - how they can be left trapped here, caught in a loop, replaying the same tragedy that killed them over and over again. He understands that they are not necessarily evil, but Dean interrupts and disagrees - he doesn't like them. Suddenly, he notices a hidden door in the room, leading to a dusty, cobwebbed room.
They find Mrs Greeley's body, hung from the ceiling. She didn't want to live without her husband, so she killed herself. Sam insists they cut the body down and bury her, saying that they need to put her to rest. Molly asks what happens to them after they are put to rest. Dean says he doesn't know and doesn't care. Sam admits he doesn't know, but he believes that they are sending them to a better place.
Sam says to Dean that he wants to tell Molly about her husband. Dean says it's for her own good that they don't. However, Molly overhears part of the conversation and demands to know what happened to him. Before the boys can answer, they hear a radio begin playing "House of the Rising Sun". Dean goes to take a look and finds an old dusty radio that isn't even plugged in. The glass window on a door ices up and the words "She's mine" are revealed on the glass. Greeley suddenly attacks and takes Molly - the boys chase them but loose the trail.
Unable to find Molly, they concentrate on finding Greeley's body instead. They find a picture in a photo album that shows them the most likely spot. They head off to find it.
Meanwhile, Greeley has Molly hung up by her hands from the ceiling. He wants to hurt her, cutting into her skin bit by bit.
The boys find both the gravesite and Molly. While Dean fights Greeley, Sam digs for the corpse. Although a ghost, Greeley seems to have some telekinetic ability and almost manages to stab Dean when Sam succeeds in burning the body. Greeley vanishes. They boys and Molly head back to the Impala to get out of there.
Molly insists that she still wants to know what happened to her husband. She thinks he's dead, but Sam confuses her by revealing that David is alive. They agree to take her to him. They pull up outside a house and Molly goes to the window. She sees David inside, alive and well, but he looks older. And he is with another woman. Sam explains that the woman is David's wife.
He tells Molly the truth - 15 years earlier, she and David were in the car when they hit and killed Greeley. David survived, but Molly died. Every year, she has been appearing on that same highway, unaware that she is a ghost. Several people died on that same patch of highway after seeing the ghost of a woman being chased by a man. Her body was cremated rather than buried, so they cant put her to rest that way. The only way they can stop it is by letting her see the truth.
She wants to tell David that she still loves him, but Sam insists he knows that and is getting on with his life. He encourages Molly to let go. Once she does that, her spirit can finally be at rest. With a final acceptance, she walks towards the sunrise and dissolves into a ray of light.