The film was advertised as being Shyamalan's first R-rated film; it held its premiere in New York City on June 10, 2008, and was later released on June 13, 2008 in the United States. It received mostly negative reviews from critics, but grossed $163 million worldwide against its $48 million production budget.
In New York City's Central Park, people begin committing mass suicide. Initially believed to be caused by a bio-terrorist attack using an airborne neurotoxin, the behavior quickly spreads across the northeastern United States. Elliot Moore, a high school science teacher in Philadelphia, hears about the attacks and decides to go to Harrisburg by train with his wife, Alma. They are accompanied by his friend Julian and Julian's eight-year-old daughter Jess. Julian's wife is stuck in Philadelphia but is expected to meet them in Harrisburg. The train loses all radio contact en route and stops at a small town. They receive word that Philadelphia has been attacked by the toxin and Julian's wife was not able to get on the train to Harrisburg, instead taking a bus to Princeton. Julian decides to go look for her, leaving his daughter with the Moores while he hitches a ride. However, when they get to Princeton, it has already been hit by the toxin. Succumbing to it, the driver runs the car into a tree and Julian commits suicide.
Elliot, Alma, and Jess hitch a ride with a nurseryman and his wife. The nurseryman believes that plants are responsible, as they can release chemicals to defend themselves from threats. The group are joined by other survivors and split into two groups, with Elliot, Alma, and Jess in the smaller group. When the larger group is affected by the toxin, Elliot realizes that the plants are targeting only large groups of people. He splits their group into smaller pockets and they walk along, arriving at a model home. Two other groups arrive on the property, triggering a neurotoxin attack, signaled by what appears to be wind blowing through the vegetation. The next house they come upon is sealed, its residents trying to protect themselves from the toxin. Elliot's attempts to reason with them are deemed unsuccessful when the residents shoot Josh and Jared, two teenage boys whom Elliot had earlier befriended.
Elliot, Alma, and Jess next come upon the isolated house of Mrs. Jones, a negative, elderly eccentric who has no outside contact with society and is unaware of the current disaster. The following morning, Mrs. Jones becomes infected with the toxin. Realizing that the plants are now targeting individuals, Elliot locks himself in the basement but is separated from Alma and Jess, who are in the home's springhouse out back. They are able to communicate through an old talking tube, and Elliot warns them of the threat. He expresses his love for her before deciding that if he is to die, he would prefer to spend his remaining time with her. The three leave the safety of their buildings and embrace in the yard, surprised to find themselves unaffected by the neurotoxin. The outbreak has abated as quickly as it began.
Three months later, Elliot and Alma have adjusted to their new life with Jess as their adopted daughter. On television, an expert, comparing the event to a red tide, warns that the epidemic may have only been a warning. He states that humans have become a threat to the planet and that is why the plants have responded aggressively. Alma discovers she is pregnant and embraces Elliot with the news.
In the Tuileries Gardens at the Louvre Palace in Paris, France, a scream is heard and everyone freezes in place as the wind rustles through the trees, signifying another attack by the plants.
In January 2007, M. Night Shyamalan submitted a spec script entitled The Green Effect to various studios, but none expressed interest enough to purchase it. Shyamalan collected ideas and notes from meetings, returning home to Philadelphia to "rewrite" it, and finally 20th Century Fox greenlit the project. Now titled The Happening, the film was produced by Shyamalan and Barry Mendel and was the former's first R-rated project.
On March 15, 2007, Shyamalan described the film as "a paranoia movie from the 1960s on the lines of The Birds and Invasion of the Body Snatchers". An India-based company, UTV, co-financed 50% of the film's budget and distributed it in India, while Fox took care of other territories.
Later in March, Wahlberg, with whom Shyamalan had been negotiating at the same time as his deal with Fox, was cast into the lead role of the US$57 million project. Shyamalan had previously cast Wahlberg's brother Donnie in The Sixth Sense.
Production began in August in Philadelphia, with filming on Walnut Street, in Rittenhouse Square Park, in Masterman High School, on South Smedley Street, and at the 'G' Lodge in Phoenixville. The release date was June 13, 2008, intentionally set for Friday the 13th to suit the thriller also filmed in Michigan.
Rotten Tomatoes, a review aggregator, reports that 18% of 173 surveyed critics gave the film a positive review; the average rating is 4/10. The consensus reads, "The Happening begins with promise, but unfortunately descends into an incoherent and unconvincing trifle." At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the film scored a 34 out of 100 based on 38 reviews.
On June 8, 2008, days before the first few reviews for the film came online, Shyamalan told the New York Daily News: "We're making an excellent B movie, that's our goal". Some critics enjoyed it because of this. Glenn Whipp said, "Tamping down the self-seriousness in favor of some horrific silliness, M. Night Shyamalan's The Happening plays as a genuinely enjoyable B-movie for anyone inclined (or able) to see it that way".
Kirk Honeycutt of The Hollywood Reporter said the film lacked "cinematic intrigue and nail-biting tension" and that "the central menace [...] does not pan out as any kind of Friday night entertainment". Variety’s Justin Chang felt that it "covers territory already over-tilled by countless disaster epics and zombie movies, offering little in the way of suspense, visceral kicks or narrative vitality to warrant the retread". Mick LaSalle wrote in his San Francisco Chronicle review that he considered the film entertaining but not scary. He commented, too, on Shyamalan's writing, opining that, "instead of letting his idea breathe and develop and see where it might go, he jumps all over it and prematurely shapes it into a story". James Berardinelli said the film had neither "a sense of atmosphere" nor "strong character development"; he called its environmental message "way-too-obvious and strident," gave it a star and a half out of a possible four, and concluded his review by saying, "The Happening is a movie to walk out of, sleep through, or—best of all—not to bother with." Time’s Richard Corliss saw the film as a "dispiriting indication that writer-director M. Night Shyamalan has lost the touch". The Chicago Tribune’s Michael Phillips thought the film had a workable premise, but found the characters to be "gasbags or forgetful". Joe Morgenstern of The Wall Street Journal said that the film was a "woeful clunker of a paranoid thriller" and highlighted its "befuddling infelicities, insistent banalities, shambling pace and pervasive ineptitude".
Stephen King liked the film, stating: "Of Fox's two summer creepshows [the other being The X-Files: I Want to Believe], give the edge to The Happening, partly because M. Night Shyamalan really understands fear, partly because this time he's completely let himself go (hence the R rating), and partly because after Lady in the Water he had something to prove". Critic Roger Ebert of the Chicago Sun-Times, awarding the movie three stars, found it "oddly touching": "It is no doubt too thoughtful for the summer action season, but I appreciate the quietly realistic way Shyamalan finds to tell a story about the possible death of man". William Arnold of the Seattle Post-Intelligencer called it "something different—and a pleasant surprise" among that summer's major Hollywood releases, and approved of its taking "the less-is-best approach." The New York Times’ Manohla Dargis praised Wahlberg's lead performance, adding that the film "turns out to be a divertingly goofy thriller with an animistic bent, moments of shivery and twitchy suspense". Philipa Hawker of The Age gave it 3.5 out of 5 stars, commenting on "the mood of the film: a tantalizing, sometimes frustrating parable about the menaces that human beings might face from unexpected quarters," drawing special attention to "the sound of the breeze and the sight of it ruffling the trees or blowing across the grass — an image of tension that calls to mind Antonioni's Blowup". Richard Roeper of the Chicago Sun-Times said, "It almost dares you to roll your eyes or laugh at certain scenes that are supposed to be deadly serious. But, you know what, I appreciated this creatively offbeat, daring sci-fi mind-trip". Reviewer Rumsey Taylor said that the film moves forward with "jack-in-the-box suspense, traipsing from one garish death to another in a parade of cartoonish terror," and noted how the film seemed like "Alfred Hitchcock’s The Birds, only without the birds."
The Happening has also attracted academic attention. Joseph J. Foy, professor of politics and popular culture, describes Shyamalan's film as an expression of "post-environmentalism" in which traditional paradigmatic politics are replaced with a call for the world to "embrace a revolutionary reevaluation of wealth and prosperity not in terms of monetary net worth or material possessions, but in terms of overall well-being". Foy praises the highly complex narrative in which Shyamalan weaves contemporary environmental challenges with hard science and social theory to create a "nightmarish future that... may advance the type of dialogue that can truly change the cultural conversation".
The film was nominated for four Golden Raspberry Awards: Worst Picture, Worst Actor for Mark Wahlberg (also for Max Payne), and Worst Director and Worst Screenplay for M. Night Shyamalan.
Wahlberg offered his own opinion of The Happening in 2010, saying that Amy Adams, who was in consideration for the role of Alma Moore, had "dodged the bullet" by not starring in the film. He said, "It was a really bad movie... Fuck it. It is what it is. Fucking trees, man. The plants. Fuck it. You can’t blame me for not wanting to try to play a science teacher. At least I wasn’t playing a cop or a crook."
The Happening came in eighth in a 2010 poll by Empire magazine of "50 Worst Movies of All Time", and first in a 2012 poll by SFX magazine of "50 Worst Sci-fi & Fantasy Movies That Had No Excuse".
On its opening day, The Happening grossed US$13 million. Over the weekend, the total gross came in at US$30,517,109 in 2,986 theaters in the United States and Canada, averaging to about US$10,220 per venue, and ranking #3 at the box office, behind The Incredible Hulk and Kung Fu Panda. Foreign box office gross for opening weekend was an estimated US$32.1 million.
As of December 2009, 1,094,000 DVD units have been sold, equating to over US$21 million in revenue.
The Happening: Original Motion Picture Soundtrack was composed by James Newton Howard. It was released on June 3, 2008.