The movie starts late on a Friday afternoon at the investment bank where Harold (John Cho
) works. Two of Harold's co-workers talk about going out for the night to get laid. One, who is heartbroken from a breakup, says he can't go out because he has to work on a project due the next day. The other suggests giving the work to Harold because he is "a nerdy little Asian guy." When Harold is coerced into doing the work by threats of being reported to his boss for slacking off, he has to call his roommate Kumar. Kumar (Kal Penn
) is at a medical school application interview. He doesn't want to become a doctor but is applying to medical school so his father will keep paying for his apartment. Harold interrupts the interview with the phone call to tell Kumar he can't party tonight because he has to work. Kumar replies--in front of the dean-- "Fuck that shit, since when has doing your work prevented you from getting high?" This line of reasoning easily changes Harold's mind, and the dean's as well. Though the dean had been on the verge of admitting Kumar before he took Harold's call, he's appalled by Kumar's bad manners and bad attitude. The dean throws Kumar out of his office (but not before Kumar spills a hot drink in his lap).
Harold leaves his office where his bad day gets worse when his briefcase strap breaks and he is held up at the exit. He drives home. As he's backing into a parking spot in front of his apartment building, an Orange Ford Bronco steals the space. The group of "extreme assholes" in the Bronco tell Harold, "this is America, dude, learn how to drive" and flick him off. Harold finds another spot, many blocks away, and walks through the front door of his building to see his dream girl, Maria (Paula Garcés
), waiting for the elevator. He plays in his head how he wants the next events to go: he tells Maria that she can come over his place if she isn't doing anything else that night, and she agrees. Reality sets in and he walks into the elevator with Maria and forgets to press his floor number, which makes him look like an ass. He is about to say something to Maria but chickens out and ends up jerking his mail in his hand. The elevator gets to his and Maria's floor and they go their separate ways. Maria tells him bye, to which he replies in a low voice.
Harold gets into his apartment and the party begins! But first he has to chase Kumar out of his room and dispose of his nail scissors, which Kumar has been using to trim his pubes. Then they settle down and get high. Joint after joint after bong hit Harold and Kumar get blitzed out of their skulls. They see a TV news flash saying that a cheetah has escaped from the Morestown Zoo. Now they got the munchies. They talk about getting some KFC when a White Castle advertisement comes on the TV and they are focused on White Castle and nothing else. They ask their neighbors Goldstein (David Krumholtz
) and Rosenberg (Eddie Kaye Thomas
)--who are as stoned as Harold and Kumar--to go along, but Goldstein and Rosenberg would rather have hot dogs. On the way to Harold's car, they see the yahoos who took Harold's parking spot; the yahoos call Harold and Kumar fags.
They go to where they think White Castle is, but it's not a White Castle anymore; it's a Burger Shack. They ask the drive-thru worker what happened to the White Castle. He informs them that Burger Shack bought that location 4 years earlier. He also tells them about a White Castle 45 minutes away that is open 24 hours.
They head for the restaurant and are about to smoke some more but Harold being the paranoid smoker he is throws the weed out the window because Kumar gets stuck in a toll booth that isn't working. Kumar gets mad at Harold and decides to take him to Princeton to sweet talk Cindy Kim, who has a huge crush on Harold, into getting them some weed. Harold goes to a meeting of Cindy's club while Kumar goes around the college looking for anyone who has weed. He finds a huge stoner named Bradley (Dov Tiefenbach
) who shows him a pound of weed. Kumar catches the fancy of two cute girls in argyle sweaters, who invite him to come up to their room later. Bradley sells a very over-priced quarter of weed to Kumar. Kumar finds Harold and they smoke a joint on a staircase, which catches the attention of a Princeton security guard. The guard chases them. They escape by hiding in the women's bathroom, where they unwillingly overhear--and oversmell--the argyle sweater girls playing a disgusting game called "battleshits." The security guards catch Bradley with his pound of weed and take him to jail.
Back on the road to White Castle, Kumar stops in the middle of nowhere to take a piss. He goes into the woods and finds a random bush and starts peeing when a man (Jamie Kennedy) dressed in a suit comes out of nowhere and starts peeing next to him. When Kumar asks him what he is doing, the man starts flipping out asking him if it's his special bush and if he is "a fucking tree hugger." Meanwhile, a raccoon jumps into their car; Harold, who's working on his laptop, doesn't notice. When Kumar is done urinating he gets back into the car and drives off. The raccoon jumps into the front seat and bites Harold's neck, making him think he has rabies. He throws the raccoon out the window.
They go to the hospital where they find out that Harold doesn't have rabies, but Kumar's father, a doctor, catches them before they can leave. He questions Kumar about the failed medical school interview and tells Kumar that he has one more interview tomorrow and if Kumar is anything less than perfect he will completely cut him off. Kumar then steals his father's ID card in hopes that it will get them access to the hospital's supply of medical marijuana. Kumar and Harold are then mistaken for Kumar's dad and brother and they're asked to perform emergency surgery on a man who has been shot. Kumar performs it flawlessly and asks the man if he knows how to get to White Castle; he gives them directions and off they go.
Harold and Kumar see Maria leaving a movie theater. Kumar yells to Maria, but Harold doesn't want her to see him so he leans down and presses the gas pedal. Kumar loses control and the car goes down a steep hill. The car is undamaged but the tire pops. Then a tow truck picks them up. It's driven by an ugly man covered with boils and sores, Freakshow (Christopher Meloni
). He takes them to his house where he tells them that he will fix their car and they can go inside and fuck his wife Liane (Malin Akerman
). To their surprise his wife is HOT!! She is a freak and she wants them to fuck her at the same time, but Harold says he doesn't want his balls touching Kumar's so they ask for blow jobs. Before they get very far, Freakshow comes in and flips out to see his wife topless and the guys about to touch her breasts. Then he lightens up and asks if they want to have a foursome, which scares Harold and Kumar and they run out.
They flee in the car (Freakshow fixed the tire), but they're lost, so Kumar picks up a hitchhiker, hoping that the guy will know how to get to the White Castle. The hitchhiker is Neil Patrick Harris
--playing himself, more or less. Neil is tripping off X and wants to pick up some strippers so he can get laid. He's no help to them. They find a convenience store where they hope to get directions. They meet back up with the "extreme assholes," who give them more shit. They get directions from a man working at the store as the "extreme assholes" tear it apart. While they are walking back to the car, Neil takes off with it.
On the way to call the police about the stolen car, Harold is arrested for getting into an altercation with a police officer while trying to cross the street. While in jail Harold sees Bradley the huge stoner, stripped down to his BVDs. Bradley's pound of weed has been confiscated and his mother takes him home. Kumar breaks into the jail and lets Harold out. Kumar catches a whiff of weed, sees Bradley's confiscated pound, and takes it. He and Harold are now running from the police. They end up in the woods where they see the cheetah that escaped from the zoo.
To make sure the cheetah doesn't kill them they toke up and get the cheetah blazed. They end up riding the cheetah in hopes that it will take them to White Castle, but Harold gets knocked off and knocked out. He has a psychedelic interlude--featuring walking hamburgers, a white castle, and lots of marijuana leaves--in which he shoots the obnoxious cop who arrested him ("Bullets--my only weakness! How did you know?") and hooks up with Maria. He wakes to find that it's Kumar, not Maria, licking his face; that his laptop has been smashed; and that the cheetah took them in the wrong direction. Now Harold, who has never been as devoted to the quest as Kumar, decides to give up and go home, hamburgerless. But just then they catch sight of their neighbors Goldstein and Rosenberg scarfing down hot dogs and looking happy. Harold decides that he craves that feeling of satisfaction that comes from getting what you want--in his case, White Castle burgers.They go back to the convenience store, where they steal the "extreme" guys' Bronco. As they speed down the road a cop starts to chase them. They turn into the woods to lose the cop and come to an abrupt stop at the edge of a cliff--where, looking down, they see WHITE CASTLE!! Kumar makes a passionate speech about their whole journey and how it's not just about hamburgers any more: it's about being in America and to have any dream you want to have and their dream is to get to White Castle.
Riding a hang glider they find on the roof of the Bronco, they jump off the mountain just as the sun comes up. They crash into a tree and land right in front of Whitecastle. They go in and each order 30 hamburgers, 4 orders of fries and 4 sodas--only to find out that they don't have any money. But Neil Patrick Harris sees them and gives Harold back his car key, says he is going to pay for their meals and gives Harold $200 for the "love stains" he made in the back of his car.
They enjoy a huge, fabulous meal. Once they finish they decide that they are going to change their lives. Kumar will go to med school and to his interview that day. When Harold's slacker co-workers walk in, he stands up for himself and tells them he isn't going to do their work for them any more. He and Kumar leave White Castle full and changed. Harold tells Kumar he is going to ask Maria out and stop being a pussy.
At home, they're getting off the elevator when Maria gets on. Kumar makes Harold go back down with her. After an awkward start, Harold spills his guts and Maria ends up making out with him and falls for him. She tells him "now you have to work on your timing;" she is going to Amsterdam and she will be back in 10 days. Harold rides the elevator back up where Kumar meets him and asks if Maria touched his penis. Harold reports that he made out with her and that she is going to Amsterdam and she will be back in 10 days. Kumar tells him that a hot chick like her in Amsterdam for 10 days is "the kiss of death" and she could come back taken. Kumar talks Harold into going to Amsterdam and it ends.Harold & Kumar Escape from Guantanamo Bay
picks up where this movie leaves off.