The movie opens with shots of people in the mall followed by shots of the parking lot where a man in a trench coat runs around flashing different women. Ronnie (Seth Rogan) is reprimanding the two Asian twin security guards saying that they made him look bad. Another guard, Dennis (Michael Pena), tells them that they hurt Ronnie and that no one hurts Ronnie. Ronnie dismisses them.
Outside of the mall, a reporter is talking to Ronnie about what happened at the mall. She calls him a security guard and he yells cut and tells her that he is head of mall security. The camera keeps rolling and he asks if shes going to keep going even though she messed up his title, so he calls her doctor.
Cut to Brandi (Anna Farris), who is a make up counter salesperson. Ronnie is watching her from a distance. She is talking to her gay friend, Bruce, about a client that she had and laughing. Ronnie walks up laughing hysterically and Brandi stops laughing. Ronnie stops laughing and asks what they were talking about. She asks why he stopped by in a way that shows that she is uninterested. He tells her about the pervert in the parking lot and to be careful. She says shell be fine.
Cut to Ronnie and the Yuan twins at the gun range shooting really accurately. They talk about guns and how much cooler it would be if the could carry guns as security guards (there is a gun ban in place). However, they can only carry tasers and mace.
Ronnie is now home with his mom watching the news where the interview from earlier that day is playing. The news shows him threatening to murder the pervert. His mom tells him that she is very proud of him. She slurs her words and Ronnie tells her that shes just drunk and she says she isnt. He confesses that part of him thinks that the pervert is the best thing thats happened to him because its his chance to be great. He goes to bed on the couch but wakes up when he hears his mom falling to the ground. He covers her up with a blanket.
The next day he gets a cup of coffee from a place at the food court where he meets a girl, Nell (Collette Wolfe), whos new. She had ankle surgery and is in a cast. Her boss comes over and kicks her leg and tells her to keep the traffic area clear and walks away. Ronnie says he disagrees with the bosss methods, but it is a fire hazard. She asks if there really is a pervert and he says yeah and that its his job to protect the people of the mall.
Brandi drives to the mall and gets out of her car. The pervert comes up to her, exposes himself and tells her to touch his dick. She screams. In the mall, shes at work, where mall security is asking her questions. Ronnie comes running in and tells the twins to set up a perimeter. The police ask her to come to their office, but she cant walk due to shock so Ronnie carries her. A detective (Ray Liotta) comes to the mall to talk to Brandi. She describes the pervert and the detective thanks her and tells her that hell talk to the other women and go on from there. Ronnie says that Brandi was targeted because shes the prettiest person in the mall and that the pervert will come back to finish the job, which means murdering Brandi. She starts to freak out, but the detective calms her down and leaves. Ronnie gets upset because this was supposed to be his case and now the detective is taking over.
Ronnie holds a meeting with all the other guards and explains that they need to catch the pervert. He instructs them to report to him only and dont talk to the police. Later that night, someone breaks into the mall and steals a bunch of sneakers. The next morning the police are called in and the detective is there again asking if the manager has seen anyone suspicious. She says no and he seems satisfied and is about to leave when Ronnie asks her who robbed the store. She says she doesnt know and he asks her again. He then talks to a janitor who doesnt speak English and tells the detective he did it. The detective asks what he said and Ronnie says that he doesnt know because he doesnt speak Spanish. He then accuses another man so the detective asks him if hes seen anyone suspicious. It turns out that the man accused has a restraining order against Ronnie and that Ronnie accused him of having intentions to bomb a Chick-fil-A.
The detective and Ronnie are in the office of mall security and the detective goes off on Ronnie saying that he messed up the investigation and he wasted the whole day getting nothing because Ronnie is incompetent then he storms out.
Ronnie enters a police station to find out what they are looking for in an applicant. The recruiter gives him some forms to fill out for a background check. He mentions that Ronnie can take a ride along where he can ride with a police officer to see what a typical day would be like. Ronnie fills it out when he gets home.
He goes to work the next morning and gets coffee from Nell. He says that the coffee tastes different and mentions that he applied to become a police officer.
The detective comes out of the police building and gets into his car. Ronnie is in the back seat and scares him. He says that he is there for his ride along and he cleared it with the captain and that paybacks a bitch. The detective drives with Ronnie in the passengers seat into a bad neighborhood and Ronnie sees all this crime going on in the streets. He stops and points out a corner that he claims is the worst corner hes ever seen. He and other officers have tried to clean it up but theres still a lot of work left. He tells Ronnie that he will let Ronnie patrol it himself that night to make it up to him for getting off on the wrong foot. Ronnie is excited for the opportunity and gets out. The detective drives off and Ronnie yells after him. A young boy and a friend approach him and ask him if he wants to buy crack. Ronnie tries to arrest him but is interrupted by the boys dad. He informs the dad that his son tried to sell him drugs. The dad says its because he works for him. Ronnie says he is going to take his son to jail, and the dad points a gun to Ronnies head. Ronnie lets the boy go. The dad says hell kill Ronnie and Ronnie gets down on his knees. Ronnie stealthily pulls his extendable police baton from out of his sock and unleashes hell. Everyone is beaten and Ronnie is the only one left standing.
At the police station the detective is laughing with his friends who cant believe he left Ronnie on the corner. Ronnie comes into the station yelling for the bad guys to sit down. He accuses the detective of setting him up. The detective admits it and asks Ronnie what hes going to do about it. Ronnie says he wants to thank him because he knew that the detective was testing him to see if he had the ability and Ronnie found out he did and that there are 6 to 8 crackheads who can confirm that. He thanks the detective for believing in him. The other detectives laugh silently as Ronnie gives him a hug.
Scenes between Ronnie training at the police academy and him at the mall making plans to catch the pervert are shown.
Brandi walks out of the mall at night by herself and she thinks someone is following her so she starts to run. It turns out to be Ronnie in a little security car and he offers her a ride. He asks her out to dinner and she points out her car. He keeps driving and refuses to stop until she agrees to go out with him. She says fine and tells him to pick her up next Friday. He starts stroking her hair and she tells him to stop.
Nells boss goes off on her again for not keeping her area clean. Ronnie comes for a cup of coffee and asks if shes married because she wears a ring. She says its a purity ring but shes not a virgin, shes a born again virgin. Ronnie says he thought if she was married, she could help him with his date with Brandi.
Ronnie is home getting ready and his mom says he looks really handsome. She talks about her first date with his dad. Ronnie asks why he left and she says that he freaked out when Ronnie was born and couldnt take the pressure. He asks if she thinks its his fault that his dad left and she says definitely.
Ronnie is waiting outside Brandis place when a car drives up. Brandi gets out of the car and sees Ronnie and asks what hes doing there. He says they had a date and she says she forgot and its late. Ronnie says its OK because he made several reservations. Theyre at a restaurant/bar and Brandi downs a big glass of alcohol. She calls the waitress nurse and asks her for shots of tequila. She talks about how much she hates working at the mall. Ronnie pulls out some prescription pills and Brandi is impressed because she didnt think he partied like that. He claims he parties like that... looks at the instructions on the bottle, "every 4-6 hours." She asks for one and he gives her the whole bottle. She admits that she thought the date was going to suck because she thought he was weird. She downs several shots and then Ronnie takes her home on his motorcycle. She can barely walk and Ronnie kisses her and takes her into her house. He is having sex with her but she seems passed out. He stops and she asks why he stopped so he continues.
Ronnie is at the station getting a psych exam and tells the psychiatrist that he took medication for bipolar disease but is currently off. She asks him why his doctors took him off and he says they didnt. She asks him why he wants to be a police officer and he tells her he has this dream where everyone is happily playing in the park but a dark cloud of bad things comes and he steps up and shoots it with a shot gun and then everyone thanks him. Then he starts using his fingers as guns and shoots the psychiatrist, which makes her uncomfortable.
Ronnies security guard friends and his mom throw a congratulations party for him. The cake is in the shape of a gun and his mom starts crying and saying how proud she is of him. Dennis gives her a tissue and she starts flirting with him.
Brandi is working and putting make up on a customer, when Ronnie stops by with a rose and starts stroking her with it. He tells her to wait for him. Ronnie walks to the food court where Nell tells Ronnie to wait as she wheels herself out from behind the counter to give him his coffee. He smiles and walks out as she watches him. Ronnie arrives at the police station and knocks on the detectives door. The detective is with his friend and says dont say anything or hell give it away. He tells Ronnie to enter. He tells Ronnie that he cant join the academy because he failed the psychological exam. The psychiatrist wrote that Ronnie suffers from delusions and would be dangerous to others and himself. The detectives friend leaves saying that he thought it was going to be funny, but its really just sad. The detective says there is no chance of Ronnie joining the academy. Ronnie leaves and returns to the mall.
Nells boss and coworker are making fun of her when Ronnie comes up to the counter. She asks why hes not with the police, and he says he had made it and tried it out for a couple days and didnt like it so hes back. She offers him coffee, which he refuses, saying its the last thing in the world he wants. She starts to cry so he changes his mind and asks for the cup of coffee. Nell says that Roger (her boss) is so mean to her. She cant quit because of the doctor bills and insurance. Ronnie bursts into the kitchen area and bashes Rogers head into the oven. He threatens to murder Roger if he says one more thing to Nell. He walks out and tells Nell that he was never there.
Ronnie and Charles, one of the security guards are putting a boot on the car of the guy Ronnie accused of planning to blow up the Chick-fil-A. He starts flipping out and Ronnie tells Charles to take out his taser. Ronnie grabs it and hits the guy.
Ronnie is in the guards office when the Yuan twins come in with a clue about the pervert. Its a Polaroid of a penis, which Ronnie identifies as Charles. Ronnie opens up to Dennis saying he is a dick and puts the picture on his forehead. Dennis opens up to Ronnie saying that he looks up to Ronnie and reveals that he knows how to mess with the system. He asks Ronnie if he is ready to learn from him. Ronnie accepts.
Ronnie and Dennis do drugs, drink, graffiti walls, watch women, attack skateboarders, etc. Dennis admits to Ronnie that its him who robs the mall after hours while taking jewelry. Ronnie gets serious and says he cant be a part of it. Ronnie asks him to stop and Dennis hits him over the head with a board. Dennis steals the raffle car and drives away.
The security supervisor is yelling at Ronnie for not knowing it was Dennis and letting him get away. Ronnie has another Polaroid of the perverts penis (real one this time). The supervisor says that hell hand it over to the police. Ronnie says that finding the pervert is his last shot at redemption so he cant give it to the police. Ronnie decides to go undercover to catch the pervert. He does a Batman monologue. He sees Brandi get into her car and follows her just to see that she is having sex with the detective (Liotta). He storms into her work the next day and yells at her and blows his cover.
The detective is looking for Ronnie who wont leave the mall. He tells the police officers who are with him to get Ronnie. Ronnie starts defeating them one by one while the detective looks on. Ronnie is eventually taken down and Charles comes to the rescue. Ronnie and the detective start fighting and Ronnie is taken down and taken to jail.
Ronnie goes home and tells his mom that he lost his job. His mom starts talking but she doesnt know what shes talking about because shes drunk. Shes thankful to Ronnie for not throwing her away and shes ready to make a change by switching to beer. She gives him a postcard from Dennis in Mexico. Dennis admits that he respects Ronnie for caring so much.
Ronnie is at the food court where Nell walks up to him with a cup of coffee. He asks how much he owes her because he doesnt have free coffee rights anymore. Nell kisses him. The streaker flashes them and runs away. He is running with his jacket flapping open so everyone can see everything. Ronnie chases him and punches bomb threat guy on the way. Ronnie runs into some people and falls on the floor. The streaker stops by Brandis place and runs up to her. Brandi drops her tray of samples and Ronnie appears and shoots the pervert. The security supervisor comes and yells at Ronnie for killing him. The pervert moves and the supervisor relaxes. The Yuan twins come and point a taser at the pervert. The supervisor says to call an ambulance and Ronnie says that hell take him to the station himself. The supervisor gives Ronnie the mall keys back. Brandi says good job and Ronnie announces to everyone, "f you want a slut that will have sex with you and then fuck your sworn enemy, THIS IS THE GIRL!" People clap as Ronnie leaves.
Ronnie gives the pervert to the detectives and tell them that he doesnt need their badge or gun to know who he is. He drives off and is interviewed by the news lady and reveals that he and Nell are together and that he intends to make her break her promise to God by having sex with her.