On September 11, 2001, Port Authority Police officers John McLoughlin and Will Jimeno are patrolling the Port Authority Bus Terminal in Midtown Manhattan when they see a plane fly dangerously low overhead. As all of the Police return to the station, they see on TV that the North Tower of the World Trade Center has been hit by the plane. Sergeant McLoughlin assigns many of the officers to assist in a precautionary evacuation attempt of the North Tower and they board a Metropolitan Transit Authority bus. On the bus, they hear reports that the South Tower is also hit by another plane. When they arrive at the World Trade Center, they realize the extent of the disaster, and see one of the victims jump out of the towers to certain death. The men proceed to get safety equipment from Building 5 and enter the concourse between the towers.
The group consists of McLoughlin, Jimeno, Dominick Pezzulo and Antonio Rodrigues. Officer Christopher Amoroso appears to inform them of other events, such as the attack on the Pentagon, the second plane's hit on the South Tower and an attack on Israel though the group does not accept any of these as true. As the men prepare to enter the North Tower, the buildings begin to rumble. McLoughlin realizes that the South Tower is collapsing onto them and that their only chance of survival is to run into the service elevator shaft. Amoroso trips and does not have time to get up, and Rodrigues is unable to get to the shaft in time, resulting in both deaths. McLoughlin, Jimeno and Pezzulo manage to escape the huge amounts of dust and rubble flying down from the South Tower. However, as the rubble continues to crush the elevator shaft, the three are trapped. As the cascade of debris subsides, Pezzulo realizes he can free himself and manages to move nearer to Jimeno in order to shift the debris covering his legs, but cannot make it to McLoughlin as he is trapped deeper in the rubble. Pezzulo tries but fails to shift the debris due to its weight, and is instructed by McLoughlin not to leave.
As Pezzulo becomes optimistic that they will live, the rumbling begins again as the North Tower starts to collapse. Although Jimeno and McLoughlin are not further harmed, Pezzulo is fatally injured when a concrete slab falls into the hole, crushing his torso. After he fires a gun through a gap in the rubble to try to alert rescuers to their position, he dies. Jimeno and McLoughlin spend hours under the rubble, in pain but exchanging stories about their lives and families. McLoughlin is particularly anxious to keep Jimeno from falling asleep and Jimeno also realizes that by straining to grab a metal bar above his body, he can make a noise that rescuers might hear. Two United States Marines, Dave Karnes and Jason Thomas, who are searching for survivors, do hear it and find the men, calling for help to dig them out. Jimeno is rescued first, and then hours later McLoughlin is lifted out of the debris, barely alive and in critical condition. They are then both reunited with their distraught families at the hospital. Two years after the attacks, McLoughlin and Jimeno attend a barbecue with their families: McLoughlin's wife Donna, Jimeno's wife Allison, daughter Bianca, and their newest addition Olivia.
The epilogue states that John and Will were two of the 20 people pulled out alive and are now retired from active duty. Dave Karnes re-enlisted in the Marines.
The Port Authority police officers who are played by Cage and Peña, John McLoughlin and Will Jimeno, and their wives, played by Bello and Gyllenhaal, were involved with the writing of the screenplay and the production of the film. McLoughlin and Jimeno said they wanted to have a movie made to honor their rescuers and comrades who died on September 11, not for personal gain.
McLoughlin's wife Donna has said: "We got involved because we felt it needed to be done accurately. We wanted to do the right thing and I think the filmmakers wanted to do the right thing too." Both John McLoughlin and Will Jimeno appear at the end of the film during the barbecue scene.
The real ESU (Emergency Services Unit) police from New York who are depicted in the film—Scott Strauss and Paddy McGee—were on set as technical advisers. In addition, the firemen in the film were played by real FDNY members who served on 9/11. All of them enthusiastically supported the film and its intention to accurately portray the rescue of McLoughlin and Jimeno.
Jeanette Pezzulo, the widow of Port Authority police officer Dominick Pezzulo (who died in the attacks and is played by Jay Hernandez in the film), expressed anger with the film, criticizing McLoughlin's and Jimeno's participation in its production. She's quoted as saying, "My thing is: this man died for you. How do you do this to his family?" Staten Island resident Jamie Amoroso, whose husband also died during the rescue operation, also expressed her anger over the film and said she did "not need a movie" to tell her "what a hero" her husband was.
Many major American newspapers ran editorials accusing Oliver Stone of having his film examine 9/11 conspiracy theories because Stone was known for examining various conspiracy theories surrounding the Kennedy assassination in JFK. However, Stone has stated that the film does not explore the conspiracy theories surrounding 9/11. He, the producers, and the real McLoughlin and Jimeno, have said the film is a simple dedication to the heroism and sadness of the day with little-to-no political themes.
The film has been accused of not providing a fair portrayal of the character and motives of rescuer Dave Karnes and paramedic Chuck Sereika. They did not participate in the making of the film and felt their roles of being the first rescuers to reach the trapped men did not receive enough screen time. Sereika began treating and extricating Jimeno a full 20 minutes before officers from the New York City Police Department's Emergency Services Unit arrived.
On opening weekend, it made approximately $18,730,762 in the U.S. and Canada. In total, the film grossed $70,278,893 at the North American box office, and over $162,000,000 worldwide.
The film received generally positive reviews from critics, with a 68% "Fresh" approval rating on Rotten Tomatoes and a score of 66/100 at Metacritic.
The producers of the film met with all relevant September 11 victims groups, before production began, to inform them of the intention of the film. After its release, they, the NYPD, and the FDNY were very pleased with it. Former mayor Rudy Giuliani, former Governor George Pataki and then-Fire Commissioner Nicholas Scopetta, as well as representatives from the NY Port Authority, were at the premiere of the film at the Ziegfeld Theatre in Manhattan.
The Region 1 DVD was released on December 12, 2006 with the Region 2 release following on January 29, 2007. A special 2-disc set was also released. A 3-disc deluxe edition was produced exclusively for Target stores. Although Paramount initially dropped its support of the Blu-ray format, it came to support Blu-ray again after HD DVD's demise. The film re-appeared on Blu-ray in May 2008.