The film begins the New Jersey police department training facility and reveals a rather impressive obstacle course where new recruits are being tested.The chief tells the new recruits that they have all passed the written exam, but must complete the obstacle course to become an official New Jersey police officer.

Paul Blart (Kevin James) is able to get through rather impressively for someone of his stature, but just as things are looking good, he passes out on the ground, asleep and snoring.At home, Blart is having dinner with his mom (Shirley Knight) and daughter Maya (Raini Rodriguez), who both try to cheer him up. Blart has hypoglycaemia, which means that he will pass out if his body runs low on sugar. His mom gives him pie to help him heal.Blarts mom wants him to start seeing someone again, but he explains that Black Friday is coming and he will be very busy.

Blart is very serious about his security job and focuses entirely on that, but his daughter wears him down and convinces him to get on an online matchmaking service. Blarts ex-wife had married him for the green card, had a daughter with him, and then abandoned them.The next day, Blart sets off for work on his Segway (an electric scooter), pursued by a small dog. Blart tries his best to out-manoeuvre the dog but ends up running it over (I think it survived).At the mall, Blart is patrolling the place; keeping the peace and helping the shoppers find what theyre looking for. Blart seems to be rather good at his job, but not entirely happy.

As he patrols, he passes by a little shop-kiosk and the owner, Amy (Jayma Mays) gives Blart a warm smile. Blart is obviously enchanted, and is distracted enough to run face-first into a parked car (one of those in-mall car displays).At the security HQ, he uses the cameras to zoom in on Amy and just cant take his eyes off her, until his co-worker comes in to discuss Blarts proposal for easing mall traffic. It is evident that the other guards have nowhere near as much enthusiasm for their job as Blart does. Just then, one of the guards brings in a rookie Veck Sims (Keir ODonnell). It's Blarts job to train Veck.As they patrol, Veck asks Blart why he chose the job, who tells him about his aspirations of being a state trooper, but hampered by his condition; Veck on the other hand failed high school and cant really do much else. During this conversation, the two are circling the service tunnels under the mall and the rookie gets a little lost, but is guided by Blart who seems to know the place like the back of his hand.Blart informs Veck on how to deal with violent customers they dont have guns, so they must verbally subdue people. Blart demonstrates just how pointless it is when he tries to slow down an elderly gentleman who is speeding on his electric wheelchair.

The man drives on, tossing Blart aside.Later, Blart cruises around Amys kiosk until she notices him, and introduces himself. She doesnt seem too interested but he asks her about hair extensions (what she sells). Amy then recognizes him as the guy who crashed into the car earlier. Amys birthday is coming up but has to forgo it due to Black Friday, and ends up selling Blart a wig. As Blart and Amy say their goodbyes, Stuart (Stephen Rannazzisi) comes in and makes fun of Blart about his job, his weight, and generally being a jerk. Stuart (a pen salesmen) takes the chance to invite Amy to happy hour with the other mall workers, but she doesnt seem too impressed.That night, Blart shows up at the bar and Amy seems glad to see him, but Stuart comes in and tries to make him look bad. It is evident that Amy is disgusted by Stuarts behaviour and walks off.

Stuart continues to make fun of Blarts job and generally acting like he is much better than Blart until Veck shows up to support Blart; Stuart walks off.Blart settles in for some food with his coworkers and Vijay (Erick Avari) judges and nacho eating contest between Blart and Leon (Jamal Mixon). Blart accidentally eats a pepper and grabs a pitcher of lemonade from Veck and drinks half of it, only to realize that its a margarita this causes Blart (who never drinks) to get hammered. Blart stumbles around and makes a fool of himself in front of Amy and scares her off. He then proceeds to do a one man mosh-pit on the dance floor, knocks over the band, and throws himself through the bars glass window.

Back at home, Blart is severely depressed. He looks at his computer and sees the match-making website; he decides to check for women who match him, which results in zero matches. Blart then sees the receipt for the wig he bought, signed by Amy and starts to cry. Maya comes in to cheer him up and sees a tattoo on his but, which he got while in a drunken stupor (its a tattoo of the loch ness monster).The next day, at the mall, Blart tries to talk to Amy, who is still a bit turned off by his behaviour the previous night. Before Blart can say more, she makes an excuse to get back to work, telling him to text her if he wants to talk. Blart goes to his friend, Vijay for advice. Vijay sells cell phones at his own kiosk and lends Blart his daughters phone so that Blart can text Amy.At the back of the mall (the service entrances) a group of men prepare to break into the mall Die Hard style (locking down the mall).

At the bank, the Amy, Stuart, and Veck are there to cash in their paychecks (its Friday night) and Stuart takes the chance to further hit-on and disgust Amy. Blart is heading to the back as well, but the man who runs the arcade asks Blart to help him close up shop.The criminals are now in place all over the mall. At the arcade, Blart decides to play Guitar Hero to cheer himself up. Outside the arcade, the robbers have begun evacuating the store, causing much panic but, Blart does not hear any of this because of the video games loud music.The robbers quickly subdue the other security guards and proceed to hijack the bank, which Amy, Stuart, Veck, Leon and Maya (who was waiting for her dad) still inside, they are now hostages). Amy asks Veck what they should do, but Veck reveals himself as one of the robbers, and not only that, hes the leader.Outside, the cops arrive, along with Sergeant Howard (Adam Ferrara), who takes charge of the situation and instructs the other officers to hold their positions while the rest of the civilians are evacuated.Back at the arcade, Blart gets a phone call from Vijays daughters boyfriend Pahud (Adhir Kalyan); Vijay had lent Blart his daughters phone. Pahud gets into a jealous rage, and then breaks down in heartbreak over his break-up with Vijays daughter. Pahud notes that he knows where Blart is and hangs up.Blart is a little puzzled, but decides to forget about it, then turns around to realize that the mall is now completely empty but brushes it off since its close to closing time.

As he rides his scooter back to the security office, Blart starts to notice that something is not right.At the bank, Veck is instructing his accomplices to steal codes from each stores credit card machine they intend to steal credit card numbers. Veck then instructs all of the hostages in the back to give up all their cell phones, but Amy manages to sneak her phone into her boot. Veck takes the opportunity to harass Stuart, who is apparently quite cowardly.At the malls rear entrance, a SWAT team tries to sneak in but the robbers have already rigged the doors with explosives and using the malls security cameras to track any incoming forces.Sergeant Howard begins negotiations with Veck who makes the police think that he is trying to drill into the safe (he holds a power drill to the phone).

Howard follows the rules of negotiation without much success.Blart continues his rounds and encounters one of the robbers, thinking that he is a lost customer, until the man pulls a shotgun on him. Blart gets away, calls 911, and connects with Howard. Sergeant Howard instructs Blart to leave the mall and not get into the way, but as he gets to the entrance, he sees Amys car and realizes that she is still inside. Blart goes back into the mall to save her.The sergeant isnt too happy about it, but at least now they have a man on the inside.Blart texts Amy and proceeds towards the bank, and now pursued by two very acrobatic criminals who chase him through the mall, Parkour style. Blart tries to lose them by climbing into a ventilation shaft. Unfortunately, his grumbling stomach echoes through the shafts and is easily located.

Blart continues to climb through the vents as the criminals try to impale him with sports equipment. All the struggling causes the vent to crash and knock out one of the robbers; the other gets away. Blart discovers numbers on the unconscious robbers arm (the security codes for the credit card machines) but dismisses it, and makes his way towards the bank.Outside, Commander Kent (Bobby Carnivale) and the rest of the SWAT teams arrive and take charge. Kent calls Veck, but negotiations go nowhere. While Veck and his fellow robbers try to figure out their next move now that they are one man short, and have a security guard to deal with Amy speaks to Maya, and realizes that she is Blarts daughter. Maya also reveals that Blart talks on and on about Amy and how he feels about her. Amy is touched.

Amy secretly calls Blart and tells him that his daughter is a hostage too, and Blart is able to talk briefly to Maya. He swears that he will get them all out.Blart sneaks by the bank and tosses in the unconscious robbers skateboard, causing diversion. While Veck and the others investigate, Blart is outside putting together traps, MacGyver style.Blart makes a quick detour to pick a Birthday card for Amy, and realizes the numbers on the robbers arms are for the credit card machines. Blart uses this information to draw out Veck, who needs the codes. Blart is halfway to making a credible threat to Veck, but passes out due to low blood sugar. Luckily, Blart finds a moldy old lollipop on the floor and gets back in the game. Blart draws all the other robbers into a Rainforest Café where he has set up all his traps. The noise and movement inside the restaurant prevents the robbers from finding Blart, and he is able to sneak up on them one at a time, recording the codes on their arms on his cell phone.Veck confronts Blart and he wants his codes back. Before anything can be done, one of Blarts traps go off, causing a huge explosion that rocks the mall. Blart takes the distraction to escape.

Now there are only two left. Veck works it out that one of his hostages is helping Blart, and threatens Stewart (the coward) into telling him. Veck takes the phone, and Amy is further disgusted.The final robber is tracking Blart and is distracted by a moving robot toy, just as Blart, dressed as a hockey-player mannequin comes out from behind and knocks him out. Veck searches for dirt on Blart and sees a picture of Maya, and realizes that she is Blarts daughter, whom Veck uses to threaten Blart. This causes Blart to be even more determined to stop Veck and they head for a final showdown.Outside the bank, Veck sees Blart on his scooter and opens fire, only to realize that its a decoy. Back at the bank, Blart is trying to lift all the hostages into the vent shafts above. Veck runs back and is able to stop them. Veck knows that Blart stored the codes in the phone and threatens the hostages.Blart tosses the phone to Veck and while hes distracted, Blart sprays hot sauce into Vecks eyes. Unfortunately, Blart stalls and Veck recovers, and orders everyone to leave in a van by gunpoint.Blart runs after them, stealing the minivan that he had crashed into earlier and gives chase. Commander Kent gets into the minivan with Blart and they chase after Veck. Blart has an idea and calls Pahud, getting him to use the GPA tracking in his girlfriends phone to locate Veck.

Kent and Blart close in on Veck and Blart climbs on top of the minivan and attempts to land on top of Vecks vehicle, only to fail miserably and end up in a ditch. However, Blart takes a shortcut through a forest and intercepts Veck at an airstrip. Veck and Blart fight but Blart passes out again but this time its just an act, catching Veck off guard and taking him down. As Blart cuffs Veck, Kent arrives to congratulate Blart, then pulls a gun on him. It turns out that Kent was working with Veck. Kent is about to shoot everyone to remove witnesses but the chief of security at the mall shoots the gun out of his hand (having just arrived with Sergeant Howard and his men).

As everything resolves, Blart walks confidently to Amy and gives her a Birthday card with a sappy yet sentimental message, and Amy kisses him.Sergeant Howard offers Blart a job with the State troopers but Blart decides that he is already where he wants to be.