In Pittsburgh, Pennsylvania, a man drives a van into a parking garage across from PNC Park. After paying for parking, he readies a sniper rifle and tragically takes aim, seemingly targeting five random individuals near the stadium and along the river's North Shore Trail, before hastily fleeing the scene in his vehicle.
The police quickly respond, led by Detective Emerson, who discovers a shell casing alongside the coin used for parking. A fingerprint from the coin reveals the suspect to be James Barr, a former U.S. Army sniper. When the authorities raid his house, they uncover the van, sniper rifle, and bullet-making equipment, leading to Barr's arrest.
During an interrogation conducted by Emerson and the District Attorney, Alex Rodin (Richard Jenkins), Barr scribbles "Get Jack Reacher" on a notepad. Reacher, portrayed by Tom Cruise (Tom Cruise), is a drifter and ex-U.S. Army Military Police Corps officer, who makes his way to Pittsburgh after catching news of Barr's involvement in the shooting. Although Emerson and Rodin refuse Reacher access to the evidence, they permit him to meet Barr, who is now in a coma following a brutal attack in transit.
There, Reacher encounters Barr's defense attorney, Helen Rodin (Rosamund Pike), the District Attorney's daughter, who is determined to save Barr from facing the death penalty. Helen proposes that if Reacher assists her as a lead investigator, she can facilitate access to the evidence. However, Reacher firmly states he holds no interest in exonerating Barr, revealing that Barr had previously committed a similar act during his Iraq tour, evading prosecution due to the significance of the victims’ investigations. Reacher made a solemn vow during his service that if Barr were ever implicated in further violence, he would personally intervene.
Despite his reservations about Barr's guilt, Reacher is intrigued as to why Barr requested his involvement. After agreeing to investigate, he charges Helen with visiting the victims’ families to gather insights into those tragically murdered that day. Through his examination of the crime scene, Reacher notes inconsistencies which prompt him to hypothesize that a trained shooter might have executed the killings from the refuge of the van parked on the nearby Fort Duquesne Bridge.
As Helen relays her findings about the victims to Reacher, he theorizes that the owner of a local construction company was, in fact, the main target, with the killing of others merely a cover-up. Following a bar skirmish that leads to Reacher being framed for the murder of a young woman—a key player in instigating the fight—he feels an unstoppable urge to continue his investigation. The young woman, before her untimely demise, reveals to Reacher that she was working for a man known only as the Zec.
Through further inquiries, Reacher suspects that Barr might have been framed. The sole evidence against Barr remains a coin with his fingerprint allegedly used for parking. He believes Barr’s request for him stemmed from an expectation that he would surely uncover the truth, regardless of their shared history. Pushing onward, Reacher identifies a car trailing him, linked to a Russian mafia front, who were implicated in acquiring the targeted construction company.
Reacher's relentless pursuit leads him to a shooting range owned by a former U.S. Marine, Gunnery Sergeant Cash, who tests his sniping prowess before divulging information about Barr's purported talents. However, Reacher contests this notion, asserting that Barr wasn't as skilled as claimed during their service. Video evidence links Barr to a mafia representative, suggesting a conspiracy at play.
Eventually, Reacher learns that Helen has been kidnapped by the Zec and his accomplices—including the corrupt Detective Emerson. In an explosive confrontation, Reacher, with Cash’s assistance, manages to outsmart the gang's guards. Confronting Emerson, Reacher deduces the truth behind the parking meter evidence, leading to a standoff with the Zec, who is ultimately dispatched by Reacher.
With the authorities now chasing him as a fugitive, Reacher finds solace in the belief that Helen will clear his name. When Barr finally stirs from his coma, he admits to Helen that, despite his foggy memories, he feels he must be guilty. However, his recreation of the event only serves to validate Reacher's theories, revealing the deeper conspiracy entwined in this violent tale, while Barr's readiness to accept his fate is a chilling conclusion to this chaotic saga.
