1.13 Route 666

Martin Robinson is driving on a deserted stretch of road, listening to the radio. It starts to cut in and out so he turns it off. Headlights flash into car. The man looks behind, only to find a large truck behind him trying to run his car over. Picking up speed, Martin tries to get away from the truck. After hitting him twice, he then looks behind him again to find that it isn't there anymore. The radio turns on again. Turning back around he finds the large truck in front of him. Martin turns around and the truck gives chase, ramming him off the road with a spectacular flip. The truck pulls up to the wreck for a moment, then vanishes.

At a gas station Sam is trying to explain a way to get to Pennsylvania to Dean, who is on the phone listening to a message. When Dean hangs up, he tells his brother that they are not going to Pennsylvania, but to help out and old friend whose father died the previous night. She would "never" call if it wasn't important. While Dean is driving, Sam tries to pry into Dean's affairs by defining what an "old friend" meant. Her name is Cassie, and Dean and her apparently went out for a couple of weeks. Dean also told her the "family secret" - we do what we do and we shut up about it - which gets Sam annoyed, because he had to lie to Jessica for a year and a half.

When they arrive at Cape Girardeau, Cassie and her father's friend Jimmy both work for the paper and are meeting with the mayor about the death of her father and Clayton, another black man - seemingly run off the road. The mayor isn't helpful. Dean introduces Sam to Cassie. Cassie and Dean obviously have feelings for each other, with the way they are looking at each other. Back at Cassie's house, she explains to Dean and Sam that she is worried about her mother because she is very panicky. The murder before her father was his car dealership partner, Clayton Soames. In the days before his death, her father reported being followed by a black truck. Cassie reports that there were only one set of tracks at each site, with no signs of a collision for both Martin and Clayton, so the official versions on both are 'lost control of his car'. However, both cars looks like they had been slammed into by something big. Cassie ended things with Dean when he told her the truth about hunting, but she can't explain this so she called him for help. Cassie's mother arrives but is clearly upset, not wanting to answer questions.

Out in the night, the black truck has run Jimmy off the road, killing him. The truck disappears. The next day, the area is all taped up. Harold Todd and Cassie are arguing about all the deaths. Cassie believes the roads should be shut down but he won't shut down the main road in and out of town. There were again only one set of tire tracks, so it is labeled as an accident. Cassie accuses the Mayor of being racist, but he gets offended and tells her to talk to her mother.

That night Cassie is at home when the lights flicker and the black truck pulls up outside. She closes the shutters and starts to panic. The truck keeps lunging at the house. She picks up the phone and calls Dean. Later that night Dean, Sam, Cassie, and her mom were all there. Dean asks about the driver, but she couldn't see one. Cassie said the truck just disappeared. Dean believes whoever is driving the truck wants them scared. Sam questions Mrs. Robinson about how her husband kept seeing the truck before he died. She said he was delusional, but Dean pressures her into telling the truth. She confirms her husband Martin knew who the truck belonged to - Cyrus Dorian. She mentions he "died" and Dean catches the slip. Cassie's mom and Cyrus dated forty years ago, but she was also secretly seeing Martin because of their interracial relationship. She broke things off with Cyrus and planned to marry Martin; the date they set was the day someone burned down the church while a children choir was in it. They all died. When Cassie's mom broke things off with Cyrus, he found out she was going to marry Martin. This was when the mysterious black murders occurred with the black truck. Martin and Audrey eloped, not wanting all the attention. However, on the night of the date of the wedding, someone set the church on fire, killing the children's choir. The last attack Cyrus had was on Martin, except this time Martin got loose and beat Cyrus to death. Martin and his two friends put Cyrus back into the truck and pushed it into the swamp, now they are all dead. Dean asks about Mayor Todd not be racist. She reveals that Todd was a deputy back then and figured out that they had killed Cyrus, but didn't do anything to Martin and his buddies because he also knew what Cyrus was doing too. That was why he also died. Cassie asks why Mom didn't tell her before, but Mom replies she thought she was protecting them, but there's no one left to protect. Dean pointedly disagrees, meaning Cassie.

That night Dean and Sam are outside the Robinson home, talking. Sam misses when his life was simple, just school, exams and papers... and boring. Dean brings the conversation around to Cyrus, and the level of evil that infected even his truck. That Cyrus lay in the swamp until Todd's renovation plan awoke him, and they must dredge the swamp for the body, which isn't a pleasant thought. Cassie comes out, after putting her mom to bed. Dean tells her to look after her mother and they'll be back. Cassie tells him not to get all authoritative on her, because she hates it. He asks her nicely not to leave the house before kissing. Sam clears his throat, but Dean holds up a finger for wait a minute, then finishes kissing and heads for the driver's seat.

They figure that they need to destroy the body. They pull up the truck from the swamp and yank out the corpse, then prepare to salt and burn it. Everything goes smoothly, but then the black truck appears across the field. Dean figures the burning didn't destroy Cyrus' spirit bound within the truck, so Dean drives off to lure the truck away and tells Sam to figure out a way to burn the original truck. The truck is closely following Dean, so Dean calls Sam but he has to make another call. Sam calls Cassie, before he calls Dean back. He is trying to coordinate his location. After Dean yells the road and direction back to Sam, Sam gives Dean directions, first to turn right and then make a left. With the killer truck already hitting Baby once and now is on his left side, Dean makes a spectacular slam on his brakes and whips Baby into the turn just in time. Sam tells him to go to a very specific spot, then stop. Dean brakes precisely and turns the car as the truck stops for a few seconds, then ramps up. The truck heads right for him... and shatters apart as it reaches Dean. Dean is at the church that Cyrus burned down - Sam figured if the ghost crossed hallowed ground it would be destroyed. Dean asked how Sam knew it would work, but Sam didn't, he merely guessed.

The next day Cassie and Dean make their farewells, and while Cassie isn't sure they'll meet again Dean is confident they will. They kiss, before Dean climbs in the Impala. As Sam drives, he says he likes Cassie. He asks Dean if girls like Cassie make him wonder if it's worth it. Dean doesn't answer, merely smiles and slouches down to fall asleep.