NOTE: This spoiler was sent in by CAR2NIST who says... "I don't understand why this movie received such bad reviews. I thought the movie was great; it was fast, suspenseful, and nerve-wracking with great acting. This movie deserves better.""The Sentinel
The movie starts off with an old video footage of the attempted assassination of President Ronald Reagan. As we all know, one of his bodyguards was shot, and the bodyguard in the footage lying on the ground bleeding, fades into present day Pete Garrison (Michael Douglas) lying on the his bed, which we understand he is the wounded bodyguard from that incident.
It is 4 a.m. and Pete is up to getting ready for his work. He gets dressed and heads out to the White House, where he goes through tight security and seems to know every single person on the job really well. Pete works for the secret services, and he is one of the most trusted bodyguards around the president and the First Lady (Kate Basinger). This morning they have to escort the President and the First Lady to a local school to make a speech. The escort is well organized and smooth, and the President and his wife enjoy their visit.
In a different scene, we see Jill Marin (Eva Longoria) waiting in a bureaucratic office, and she is being checked out by a lot of guys there. She is there for an interview for the job with David Breckinridge (Kiefer Sutherland) and the job is to investigate all threats made to the presidential offices. There are threat mails and threat messages all over the wall, and David tells Jill that it is all just from today. But Jill is fit for the job, and she tells David that she was actually referred here by Pete Garrison, and David seems disturbed to hear his name.
On the way back from the school visit, the First Lady asks to be taken directly to their beach house, while the President heads back home. Pete escorts the First Lady to her room and he sends the rest of the team to lunch while he hangs back to protect her. When Pete secures the room and closes the curtains, he and the First Lady (her name in Cindy) start to kiss, and it seems they have been having the affair for a long time.
During this time, Pete's best and oldest friend in the secret service, Charlie, is shot at his own front door. Earlier in the day Charlie asked to talk to Pete in private, but seemed to not trust anyone in the office, so he told Pete he will talk to him later.
David and Jill arrive to process the murder scene. The two of them discover that this was not a random drive-by shooting. From the interview they conduct with Charlie's wife, David realizes that Charlie had found out about a certain secret within the office, and it could mean that there is a mole in the office. (Pete also found out from his informant that there is a mole in the secret service, and he will only tell if Pete will give him a million dollar).
So the investigation begins, and everyone in the office is forced to take a polygraph test or they will be fired. At this time, Pete receives a mail with pictures of him and Cindy kissing. There is a post-it on it telling Pete where to meet, so Pete went ahead. Pete is then directed to a coffee shop, where he stays waiting for about 4 hours, and when he comes out he notices that a few suspicious men are following him. Pete manages to sneak away and turned it around and begins to follow the followers. This is when undercover police cars come and want to arrest Pete, but they clear the air, and it was all just a misunderstanding. The police were following leads to some secret underground criminals, and that coffee shop was known to be their drop-off spot, so Pete realized that he was being set up.
Pete gets a call from his informant and he wants to meet him in a shopping mall with the money. But since there is a mole, the location and the meeting is exposed, and the same killer that killed Charlie is there at the scene waiting already. The informant flees, and a shoot-out begin and a couple agents are shot and when Jill and David come to the rescue, the killer sneaks out the mall by changing into different clothes.
During this exact time, the President and the First Lady are on a little trip at Camp David. One of the secret service agents, Montrose, comes up with an idea to mislead the mole with a flip of a coin to decide which transportation the President rides in, so the other one will be a decoy. One flip of a coin, the President gets loaded on the helicopter and flies home. A bazooka missile shoots down the decoy helicopter, and the President is safe. A scene then shows a group of men, angry that the president was not in the helicopter. The leader calls the mole (we don't see his face) and expresses his anger.
Pete goes home and settles down, but David and Jill and a couple agents come to have him arrested and search his house because Pete was the only person that failed the polygraph test. David and Pete get in a shouting match as things begin to get personal. (From their arguments, we learn that David is upset that his ex-wife had an affair with Pete, which Pete denied). David presents Pete with some evidence of Pete trying to hide something such as his bank transactions and all, which Pete claims he was framed (Pete is trying to hide his affair with Cindy only, but others think he is hiding a plot to kill the President). Pete knows he has to get away, so he takes down two agents and runs out the back door.
The manhunt begins, and David warns the agents that they are dealing with someone really smart, someone who's been on the job for decades and will always be one step ahead of them. Pete manages to sneak into a tightly secured restaurant where Cindy is having dinner with her friends. Pete gets Cindy alone and explains to her the set-ups and the whole situation and asks that she trust him and that he loves her.
Pete steals a car and drives himself into a countryside and uses the internet in a small shop. This is when he pays a visit to his informant but not without the help of his secret service privilege on the web, so the mole gets the information as well, and so do David and Jill and the rest of the secret services. When Pete finds his informant, the killer has already gotten to him first, and David and Jill come right as Pete as leaving. A pursuit follows, and at one point, David shoots Pete right in the back, knowing that he has a bullet-proof vest on, but Pete stands up and tells David to shoot him in the head instead. David can't and Pete gets away. (Pete was actually David's long-term partner, and David realizes that Pete might really be set up, because Pete said the reason why he is still alive is because the mole doesn't know where he's at, so if he surrenders, he will be killed.)
Pete then pays a visit to Charlie's wife late at night and tries to find out if Charlie knows anything. She tells him there is a car sitting outside her house every night since the murder. So Pete takes her car and follows the car to an apartment building. Pete sneaks inside and finds out it is the killer that killed Charlie and was at the shopping mall. They fight, and Pete kills the killer. Pete then tears the apartment apart trying to find evidence, and he finds a stash of money and passports of the group of guys trying to kill the President. He finds that they all have visas and tickets to Toronto, where the President is to meet with the United Nation for a speech the next day. Pete takes fingerprints from the killer, and calls Jill (only) to come and take care of the place with all the evidence organized and placed. Pete leaves the apartment.
Then Pete gets a call from David, saying there is nothing at the apartment, not even the body. Pete gets even more concerned about the mole's ability. So Pete then goes to a federal building and asks to process some fingerprints as priority. At this time, Cindy calls David and explains everything, including the affair, to David. Pete has to wait about four hours to lift the prints and identify the killer. This is when David comes and they make up and begin to work on the case together. They put some pieces back together and realize that one person did not take the polygraph test, and that one person is Montrose, the secret agent with the coin flips, and he is the mole!
Cut to a scene where Montrose is telling the leader of the assassins that he is going to stop the entire plot. He is willing to go to jail for treason and will not be helping them out anymore. But the leader takes out pictures of Montrose's family and says he will kill them unless he helps them out. All Montrose has to do the next day is to turn off all radios after the President makes his speech, take him through the way they want the President to go, and they will take care of the rest. Montrose complies.
During the United Nation conference, the security is even tighter. David and Pete are able to get through despite Montrose's order to not let them in. David gets a hold of Jill and tells her to tell the First Lady who the mole is. But when David and Pete barge into the conference, Montrose takes the president off the podium and escorts him to the way the assassins wanted him to go. There are shootouts and agents are hurt and killed one by one, and that leaves Montrose alone with the President. With David, Jill and Pete still going after them, it seems the President is going to be killed. But Montrose then tells the President to turn off his receiver (which is how the assassins know where he is) and tells the President to stand down while the assassins kill Montrose. David and Pete come to the rescue and shoot their way out of the building and go onto the roof, where a helicopter is waiting to pick up the President. The leader of the assassins then poses as an agent and runs towards the President with a gun. But he is shot and apprehended by Pete, and the scene fades out.
Next we see Pete is looking at the picture of him and Cindy kissing and is also cleaning out his desk. Agents all come over to say their goodbyes and give him a diaper as a parting gift. Pete is retiring, and David and Jill send him off. Pete tells David that he is going to miss this secret service thing, and asks that David join him for dinner tonight. David has reconciled with his ex-wife, and will be having dinner with her instead. They smile and part ways. As Pete is leaving, he turns around and looks at the White House. In one of the window, Cindy is looking at him, but Pete turns around, and walked away.
Special Agent Pete Garrison (Michael Douglas) figures out the mole in the White House is William Montrose (Martin Donovan) who is guarding the President. Montrose was planted by the KGB 20 years ago and is leading the investigation looking for the traitor. Montrose framed Garrison over the affair Garrison was having with the First Lady (Kim Basinger). Montrose had avoided the polygraph test. The First Lady tells Agent Breckinridge (Kiefer Sutherland) that she and Garrison are having an affair and he's being framed and not the mole. The bad guys all get killed in the big shootout at the big economic summit in Toronto. Garrison kills the last Russian guy who grabbed the First Lady. President is unhurt but several Secret Service people are wounded or killed. The affair doesn't get revealed except to the Secret Service Director and Breckinridge. Last scene, Garrison retires, gets a nice send-off from his colleagues