Theta Sorority – Eastern Iowa University
A girl, Lori, is preparing for a date and her roommate helps her pick out a halter-top. Later Lori and her date Rich park beneath a bridge on their way to a party as a figure with a hook on his right hand lurks in the shadows. As they kiss, her cell phone rings – it's Lori's father. She ignores it but as he tries to put some moves on her, a horrible scratching noise is heard as the figure drags his hook along nearby signs. The boy goes out to investigate and sees scratches appear alongside the side of his car with no one making them. Rich disappears and Lori locks the car doors and closes the windows. Something crashes on the roof and she decides to make a break for it. She turns around and sees a dead, bloody Rich hanging suspended above the car, dangling from the bridge.
Sam is trying to find their dad through records when Dean comes up with a news article on Rich's death, caused by an "invisible man." They head off to the college and pretend to be fraternity brothers to get in at a fraternity. They get information on Rich, who was a fraternity member, and they find out Lori was the witness and a reverend's daughter. They go to the church and approach Lori and Sam reassures Lori. She also tells him what she was, which leads them to conclude the killer may be part of the "Hook Man" legend. They do some research and find that in 1862 an insane reverend, Jacob Carnes, had a silver hook-hand and killed 13 prostitutes at the same location where Rich was killed.
Lori's father Reverend Sorenson drives her home and it's clear he doesn't agree with her living in a sorority, and has concerns about her roommate Taylor. At the murder site, the brothers arm up with a shotgun armed with rock salt to handle a spirit. They draw a gun on a figure... who turns out to be a local policeman who arrests them. In her room, Lori goes to bed without turning on the lamps, unaware that a figure is lurking behind the door. The next morning she wakes up and finds Taylor dead cut to death and covered in blood. On the wall is a message saying "Aren't you glad you didn't turn on the lights?" written in blood.
Dean and Sam get out of jail when Dean explains it was a pledge, and spot the police heading for the sorority. They follow and see the Reverend take his daughter home, then sneak into the sorority to check out the crime scene. Sam spots a symbol on the wall, the same symbol that was on the 1862 hook-hand. Dean figures the killings are directly related to Lori. Back at the fraternity, there's a party going on, and Sam reveals that there has been a pattern of local religious men arrested for killings they claimed were committed by an invisible man, and the spirit may be drawn to Reverend Sorenson. Sam goes to watch Lori, while Dean goes to look for Carnes' unmarked grave.
Dean finds a grave with the same symbol and starts digging, while Lori sees Sam and goes out to talk with him. Dean incinerates the corpse while Lori confesses her frustration, and she and Sam kiss. Reverend Sorenson calls them in, but he's grabbed by the hook-man figure who yanks him into the house. Sam runs up to investigate and shoots the figure, forcing it to disappear.
The sheriff talks to Sam who can't give the full story, and Dean arrives. Sam thinks the spirit has latched on to Lori, who believed her father had an affair. Dean claims he disposed of the body, but didn't get the hook. They figure that if they get the hook, they can stop the Hook Man. They do some more research and track the hook to the church where Sorenson preaches, and conclude it may have been melted down into something else. They go to the basement and use the furnace to melt down anything that is made out of silver, but then hear footsteps upstairs. They investigate and find Lori praying for forgiveness, as she's determined she's the one responsible. The figure appears in the church and the candles blow out, plunging the chapel into darkness.
Sam and Lori head for the door, but the Hook Man appears outside and they flee back into the church. He's right behind them and keeps teleporting ahead of them, wounding Sam. The figure closes in and sends Sam flying, then advances on Lori. Dean opens fire and the figure disappears, and Sam notices Lori is wearing a silver cross. Sam rips it off of her, as the invisible Hook Man drags scratches down the wall toward them.
Dean takes the cross and heads for the furnace while Sam opens fire on where he thinks the figure is. When he stops to reload, the Hook Man disarms him, but the cross melts in the furnace and the Hook Man's hook melts and then he disintegrates into ashes.
Sam and Dean give a fake story to the sheriff, who tells them to get out of town. Lori thanks Sam and they head out of town, although Sam is clearly tempted to stick around for Lori.