Eastwood's character is the sole active-duty Secret Service agent remaining from the detail guarding John F. Kennedy in Dallas, Texas, at the time of his assassination in 1963. Rene Russo, Dylan McDermott, Gary Cole, John Mahoney, and Fred Thompson also star. The movie was co-produced by Columbia Pictures and Castle Rock Entertainment, with Columbia handling distribution. The film is also highly notable for being the last film that Clint Eastwood starred in that he himself didn't direct.
The film earned three Academy Award nominations: John Malkovich for Best Supporting Actor, Jeff Maguire for Best Original Screenplay, and Anne V. Coates for Best Editing.
A sub-plot of the film is the President's reelection campaign. For the scenes of campaign rallies the filmmakers used scenes from Bill Clinton's campaign events.
Frank investigates a complaint from an elderly landlady (Elsa Raven) about one of her tenants. Frank finds a shrine of sorts to famous assassinations. Later, when Frank and Al acquire a search warrant and enter the man’s apartment they discover that the pictures in the shrine have vanished and only one remains: a much younger Frank standing behind John F. Kennedy.
Frank receives a phone call the next evening from a man who insists Frank call him “Booth” after Abraham Lincoln’s assassin. The caller admires Booth because he had “flair, panache.” He tells Frank that he plans to kill the current president. The man also seems to know a great deal of Frank’s history as a Secret Service agent. Frank reports the call to his superiors and an investigation is opened.
In a side story, Frank starts a relationship with another agent, Lilly Raines. She helps him get on protection detail for the president, a duty Frank hasn’t had for years and, because of his age, is out of shape for.
Frank’s sleuthing reveals that Booth is actually a man named Mitch Leary, a former CIA operative (a “wetboy”) who has suffered a mental breakdown and is now a psychotic killer. Leary turns out to be incredibly resourceful; he opens a phony bank account in Los Angeles and is a master of disguise. He is also proficient at gunsmithing and builds a composite (i.e. non-metallic, in this case) zip gun with the bullets hidden in a key chain, so as not to set off any alarms at security gates.
Leary taunts Frank with several more phone calls throughout the film. At one point the tracing of his call leads Frank and his fellow agents to a payphone at nearby Lafayette Park, one block from the White House. As Leary flees the scene, he is nearly run over by a passing motorist. (Frank impounds the car for fingerprints.) Leary also shows up at several public events the current president attends, knowing that Frank will be there on protection detail. At one event, Leary pops several balloons and an ill Frank causes an embarrassing scene, thinking they are gunshots.
One night Al informs Frank he's going to retire in the morning because of nightmares of how Mendoza's men were going to kill him. But he decides not to because Frank insists he needs Al’s help.
Another call from Leary the next day leads Frank and Al to an apartment building where the two spot Leary sneaking away. A chase ensues along the roofs of several buildings. It ends when Leary shoots Al and kills him, though in an ironic twist, Leary saves Frank from falling from the building's ledge. Frank is devastated about Al’s death and becomes even more determined to capture Leary.
Frank concludes that Leary will attempt the assassination in Los Angeles, at a huge fundraising event to be held at the Westin Bonaventure Hotel. Frank unnecessarily roughs up a bellhop who has lost his identification card. The incident is filmed by a local news channel and Frank is thrown off protection duty.
While he travels to the airport, another clue, a coded phone number, is discovered by Frank. He finds out that Leary had opened a bank account under a false name and had sent a large donation check to the local office of the president’s party, thereby securing an invitation to the fundraiser.
Frank returns to the hotel with the phony name and demands to see the guest seating list at the banquet taking place. He recognizes Leary in disguise at a table near the stage and rushes to stop him. Leary draws his gun and fires just as Frank jumps into the path of the bullet (he is wearing his bulletproof vest). The President is rushed immediately from the scene in his motorcade.
Leary grabs Frank as a hostage and forces him out of the banquet hall and into the hotel's external elevator. They travel upwards several stories and Leary breaks all the interior lights so nearby snipers can’t target him. Leary threatens to kill Frank and himself and also tells Frank that he saved the aging agent’s career. Frank still has his earpiece and microphone and is able to talk to Lilly and reveal Leary’s position in the elevator for the snipers. They shoot into the elevator, missing both men, but give Frank the opportunity to overpower Leary. The scuffle ends with Leary clinging to the outside of the elevator. Frank offers Leary his help but Leary lets go and plummets to his death.
Frank decides to retire and he and Lilly return to Washington. At his apartment, he finds a voicemail message from Leary, bidding him farewell believing he had succeeded in the assassination attempt. The two of them leave before the message is finished.

The film was a considerable financial success as well, earning $176,997,168 worldwide ($102,314,823 in North America, and $74,682,345 in other territories), while its budget was about $40 million.