A panicked Dean is running through the woods and finds himself face-to-face with a demonic dog. He turns and runs away but falls to the ground. The hound savages him… and he wakes up. He's been going over material on Hellhounds. Sam reveals that with 30 hours left to go, Bobby has found Lilith. Sam tries to comfort him, but Dean sees his face twist and distort.
Now that they have Lilith's name from Bela, Bobby conducts a ritual that points to New Harmony, Indiana,. Dean doesn't trust the information and Sam insists on calling in Ruby and using her knife. Dean refuses to hear it and Bobby goes to find something else. Sam goes on his own and summons Ruby with a ritual. She confirms that she knew about Lilith and didn't think they were ready. He demands the knife and Ruby says that Lilith has her guard down while on "R&R" and Ruby thinks they're ready to attack. She says they'll need more then the knife and Sam's psychic powers are enough to destroy Lilith. It's only now that he's desperate enough to use them, and she can show her now.
Dean shows up and demands the knife, and tells her to leave them alone. Dean doesn't believe she wants them to succeed and Dean slugs her. She slugs both brothers but Dean manages to grab the knife from her. When she goes after him, she realizes he's lured her into a demon's trap.
The brothers take off with the knife and load up, and Sam wonders if Ruby's right and he can take out Lilith. Dean admits that Sam is his weak spot and vice versa.
New Harmony, Indiana
Pat Fremont is getting his mail when his neighbor Tom and they exchange greetings. Pat slips Tom a note saying "Help me" and goes back to his house. The babysitter is dead in the hallway and the wife and husband are living in fear of their daughter. She comes into the room, covered in blood, and Mr. Fremont suggests she might let them go. The daughter asks if they love here and they all quickly say that they do.
Dean and Sam are trying to head out only to discover that Bobby has sabotaged the car and insists he's going with them. Further, he notes that Dean is suffering from hallucinations because of the hell hounds on his tail. they head out and Dean cranks up the radio and starts singing, insisting Sam sing along with him. A policeman pulls them over for a busted taillight, but Dean attacks the man and stabs him with the knife. Bobby pulls up as Sam realizes the officer was a demon: Dean says he can now see a demon's real face. They hide the car while Bobby explains that the closer Dean gets to Hell, the more he can see the other residents of Hell.
The Fremonts are celebrating their daughter's birthday… again. The daughter confronts Pat over the fact he tries to get the neighbor's help and then casually kills him. The parents have no choice but to serve cake, while Dean, Sam, and Bobby watch from outside. Dean notes the neighborhood is filled with demons but Bobby notes the girl has to be stopped.
The daughter has her mother read the same bedtime story again, while Dean lures out a demon disguised as a postman. Sam then kills the demon with the knife while Bobby prepares holy water. They dispose of another demon but Ruby gets the drop on Dean until Sam threatens her with the knife. She demands the knife back and warns that it's too late for Dean. Dean points out that all of the possessed neighbors have seen them. They run for it as the demons pursue and try to get into the Fremont house. Bobby intervenes, having rigged up the holy water to the lawn sprinkler system. Mr. Fremont finds them and tells them where the daughter is. They try to send him to the basement and when he refuses, Dean knocks him out and takes him downstairs. Sam and Ruby go upstairs and split up. Sam finds the mother in bed with her sleeping daughter, and the mother tells Sam to strike. He prepares to do so but Dean stops him just in time, saying it's not in the girl anymore.
While Bobby waits outside, Sam asks Ruby what he needs to do but Dean overhears and Ruby says they don't have enough time. The clock strikes midnight and the hell hounds, invisible except to Dean, enter the house. They try to seal themselves off with dirt while Ruby asks for the knife so she can hold off the hell hound. However, Dean interrupts and notes it isn't Ruby, using his newly-gained vision. Sam tries to attack her but "Ruby" sends them flying. Lilith says that she sent Ruby far far away, then kisses Sam. Sam tries to bargain but Lilith warns he doesn't have anything, and lets the hell hounds in. They start to tear Dean apart while Lilith unleashes a bolt of energy on Sam… which has no effect. Sam takes the knife and prepares to stab her, but just before he does, she leaves "Ruby's" body and vanishes. Sam, seeing his dead brother lying on the floor, holds him and begins to cry.
Meanwhile, somewhere in Hell, Dean is suspended by chains and hooks. As he is being tortured, he cries out for Sam.