On the day of her wedding, Samantha is putting on her dress with bridesmaids Ruthie and Kelly. She wonders where the bride Carlos is and wonders if she might be rushing into things. She admits that her other boyfriends never stayed around long and ended up disappearing on her. Kelly wonders about Steven, Sam's brother, who is her only other family member, but Sam doesn't know where he is. Ruthie steps out briefly and comes back with a note that was given to the priest, Father Chris. Sam reads the note, which says that "the person you're marrying is a serial killer."
A shocked Carlos goes to see Sam and he apologizes for being late. He suggests they get married right then and there but Sam wants to go through with the marriage ceremony. However, she balks at the "'til death do you part" part of their vows, and doesn't return Carlos' kiss. He starts to wonder if she's getting nervous and sees the note, but Sam refuses to let him see it. She goes to see Ruthie, who says that Father Chris said a woman wearing a red scarf gave him the note. They go outside and spot the woman, but she gets in a cab and leaves before they can get her attention.
As the couple exchange vows, Sam hallucinates Carlos with a skull face and stutters through her part of the vows. When Father Chris asks if there are any objections, a man starts coughing in the back but doesn't say anything. After the ceremony, the photographer takes pictures and Carlos' Uncle Bob, who is a twin brother of the coughing man, proposes a toast. Afterward, everyone heads for the reception except Sam, who goes back to her dressing room and reads the note again. Someone starts pounding on the door but when she goes outside there's apparently no one there. However, someone watching her turns off the lights and hides in the shadows. She runs into Father Chris, who mentions that something happened to Carlos' parents at their wedding, one of the first ones he officiated. When Sam asks what happened, Father Chris says that she should ask Carlos. Father Chris goes back in and as Sam goes to the wedding, she's unaware that Carlos is watching her from the shadows.
At the reception, Sam talks to Uncle Bob, who is with the government. He says that Carlos' parents would have approved of the marriage but they disappeared when Carlos was 16. Carlos shows up and tells Uncle Bob to shut up, warning him not to tell stories. He then wonders why Sam has been avoiding him all night and tells her to start acting as if she's happy to be his wife. He also wonders why Kelly and Ruthie have been glaring at him all night.
Sam goes back to the church and tries to call Steven. She gets his answering machine and leaves a message saying that she's starting to have doubts about the marriage. Ruthie and Kelly overhear her and Ruthie goes to confront Carlos, mentioning the note. Sam tells her to back off and Carlos says that people will say anything to turn her against them. She wants to know what they've been saying about him that's so terrible and admits that Carlos is scaring her. He snaps at Sam's bridesmaids and then leaves.
Sam follows him to the church and finds him sitting alone. He says he knows about the note but assures her that he would never harm her. Sam, scared, backs away and tries to get out. She takes refuge in the confessional booth and Carlos jams the door with a chair and enters the priest's side. He explains that he went to dinner with a woman while she was away recently, but she meant nothing to him. The woman refused to leave him alone and has been calling him ever since. He figures she's the woman that gave Father Chris the note to give to Sam.
The woman with the red scarf returns to her apartment and looks around at its contents: decapitated human heads in vats, a dead animal, and corpses wrapped in plastic. There are also photos of Sam as a child with her brother Steven. The woman removes her scarf and wig, revealing she's Sam's brother Steven. He checks the answering machine and hears Sam's message about her being uncertain about her marriage.
In the confessional, Sam looks at the warning note and Carlos wonders if they can forget the entire thing. Sam says that she knows that the problem is: the note was meant for Carlos and Father Chris gave it to the wrong person. Carlos assures her he doesn't care what the note says, and she promises to show it to him when she's ready.