This movie begins with airline owner Tom Mullen (Mel Gibson) hosting a party at his swank New York City apartment. The party is being held to unveil his latest commercial which gives background information on how Tom became a self-made multi-millionaire airline entrepreneur. Interspersed with the scene is another scene of people preparing what appears to be a kidnappers lair designed to hold a hostage.
The next scene shows Tom with his wife Kate (Rene Russo) and his son Sean (Brawley Nolte) in central park attending a science fair that Kate is a judge of. During this scene Tom's son Sean wanders away and although not shown, he is snatched and put in a white van. Tom and Kate quickly realize their son is missing and frantically begin to search for him.
The next scene has them at their apartment, receiving a phone call telling them to check their e-mail. Their e-mail has a message with a video attachment of their son, blindfolded and chained to a bed (in the kidnappers lair we previously saw being made ready). A digitally-altered voice demands a ransom of $2 million for Sean's return. The kidnapper also states that noone is to be told of this: Police, FBI, or Media outlets.
Even though the message said not to, Tom and Kate decide that someone must be alerted. They call up the FBI who quickly set up operations at the apartment, led by Agent Lonnie Hawkins (Delroy Lindo). Hawkins asks if Tom and Kate want to negotiate or give in to the ransom demands, and finds that the two already have two suitcases all prepared for a hand-off, awaiting further instructions from the kidnappers.
The scene then cuts to a small convenience store, where we see NYC Police Detective Jimmy Shaker (Gary Sinise) conducting an investigation. As he continues listening, he notices a suspicious character (Donnie Wahlberg) coming into the store buying kid's cereal and some video tapes.
The next scene shows Jimmy tailing the man to the kidnapper's hideout. Sneaking in, we see him find the locked room with Sean inside, and then see him go over to the man (named Cubby), putting a gun to his head. However, instead of arresting the man, Shaker tells him that his purchase could have tipped the Police off to their operation. It is now clear to the audience that Jimmy is running the kidnapping of Sean Mullen.
Back at Tom's penthouse, he confesses to Hawkins that a former union head of the machinist union may have had an involvement with the kidnapping of his son. Tom confides that he bribed the union president to call off a strike and the president went to jail while Tom escaped prosecution. Hawkins arranges a jailhouse meeting between Tom and the union leader in prison, but it is apparent from the meeting that the former union president had nothing to do with the kidnapping.
Shortly thereafter, the kidnapper calls with instructions regarding the drop-off of the ransom money. While on the phone, the FBI hit a major snag when they are unable to get a lock on the kidnapper's location due to technical scrambling on the kidnapper's part. The FBI suggests that their 'double' for Tom make the drop, but Tom insists he do it himself. He is also set up with a wire to record any conversations.
Tom reaches a specific street location, and his car's cellular phone then directs him to a gym. Tom is then instructed to take the money with him, and dive into the gym's swimming pool to retrieve a locker-room key. This move causes the wire on Tom to short-circuit, destroying the FBI's planted mechanism. Tom then finds the locker, and a walkie-talkie, which instructs him to put on some clothes provided in the locker, and put the money in two large duffel bags before he heads to a parked car outside to drive to the drop-off point. This leaves the suitcases in the gym, causing the FBI to question why the money hasn't moved.
Tom drives on as afternoon becomes evening. Over the walkie-talkie, the kidnapper derides Tom that he seems to have no problems with buying his way out of tight situations (such as the one with the union leader). When it seems that none of Tom's questions or requests to speak to his son are being met, he pulls off the side of the road. After awhile, the voice on the walkie grows fainter, and Tom now realizes that the kidnapper was in another vehicle close to his. Pulling back onto the road, the signal grows stronger, and the kidnapper instructs Tom to turn off towards an upcoming rock quarry. Here, he will turn over the money and receive an address to go to next.
Arriving at the quarry, Cubby shows up in a mask, demanding the money. However, when Tom asks for the address, Cubby does not do this and struggles for the money. Suddenly, two FBI helicopters appear, and Cubby grabs the money and rushes off on a 4-wheel quad-vehicle. The FBI chase him down, with Cubby firing back at them. The FBI then take a well-placed shot that hits Cubby in the neck, causing him to fall of the quad-bike. Tom goes over hoping this person will reveal where his son is, but the wound has rendered Cubby unable to speak, and he dies shortly thereafter.
The next scene shows a furious Tom back at his home, blaming the FBI for killing the only known link to his son. However, Hawkins explains that there may be a 'silver lining' to what happened. It is known that Cubby is a petty thief, who was also in league with his brother, Clark Barnes (Liev Schreiber). The FBI believes if they can locate Clark, they may still be able to save Sean.
Back at the kidnappers residence, Clark is furious over the death of his younger brother. He and Jimmy's wife Maris (Lili Taylor) are in total agreement to simply kill Sean and leave. However, Jimmy angrily reprimands both that the plan for the ransom is still going to happen.
Back at Tom's penthouse, the media have gotten word of the drop-off and Sean's kidnapping, and details are now being televised on television. Jimmy makes another digitally-altered call to Tom, giving him new instructions on where to drop off the money this time. After using the FBI's double to throw off the media, Tom attempts to follow the instructions. However, after listening to the kidnapper's instructions, Tom changes his mind. He then informs the kidnapper to turn to the local Channel 5 news and watch it for the next few hours, before disconnecting the call.
Tom then goes to the Channel 5 news station where their broadcast is interrupted for a special report from Tom. Seated behind a desk, with the $2 million ransom laid out around him, Tom then delivers a message to the kidnapper: He will not pay the ransom. Instead, he has decided to use the ransom money as a reward for information leading to the arrest or death of the kidnapper. Tom claims that the kidnapper will never get his ransom money, and will lift the reward if his son is let free.
Tom goes back to his shocked wife and agent Hawkins, who have never heard of such a tactic. Tom is able to convince his wife that this is the best strategy to get their son back. He is convinced that based on what he experienced at the first drop - the kidnappers plan on killing Sean when they get paid.
Meanwhile back at the kidnappers house, Jimmy is losing control of his crew, who now want to dispose of Sean more than ever now that a bounty has been laid on their heads. Jimmy then sets up a new plan in hopes to reign in Tom's plan.
A note is made addressing Kate, with the stipulation that she appear at a renovated Church at 2am without her husband's knowledge. Kate goes, but is soon beaten by Jimmy, who has his face masked. Jimmy threatens to gut Sean unless his ransom demands are met, and leaves Kate shaken, along with Sean's shirt covered in blood stains.
Coming back to her home, Kate is obviously shaken up and her faith in Tom's plan begins to falter. Hawkins plays on that, attempting to create a rift so that the ransom is paid - this course of action he thinks has the highest probability for safe recovery of Sean.
However, Tom has other ideas. Leaving his apartment building, he walks right out into the midst of the media gathered on his doorstep, and reports that he is now increasing the reward to $4 million.
Jimmy then calls up Tom again, allowing Sean to speak a few words, and then demanding that Tom pay the ransom. However, neither man is willing to give the other the edge, and a shouting match ensues before the voice on the other end of the line says he'll kill Sean now, and immediately a gunshot is heard! The line cuts off, and Tom and Kate fear the worst (unknown to them, Jimmy aimed at a nearby wall, the shot attempting to bluff Tom and Kate).
Back near Jimmy's place, the plan appears to have fallen apart. Jimmy goes to a nearby laundromat to think, as nearby, Clark and the technical specialist they hired named Miles (Evan Handler) load their white van to leave. Back in the house, Maris contemplates killing Sean again.
Jimmy then formulates a way to 'salvage' the situation. Calling in on his walkie-talkie, he reports that he has come across some suspects, and then goes outside, attempting to 'arrest' Mile and Clark. The two attempt to drive off, but not before Jimmy kills both of them. Planting a weapon on Miles, Jimmy is then caught off-guard when Maris emerges from the house, shooting him. Though it pains him to do so, Jimmy kills Maris in order to make his plan work. Staggering back into the house, Jimmy plants himself next to Sean's bedside, radioing in that he has found the kidnappers lair and Sean.
Tom and Kate are soon after alerted to the discovery, and are reunited with their son. AS Jimmy is loaded onto an ambulance, Tom thanks him for saving his son's life.
Over the course of the next few days, Jimmy is hailed as a hero by his peers and the public. Meanwhile, at the Mullen's, Sean is still having trouble readjusting after his kidnapping. He is scared to be left in the dark, and his eyes have not yet readjusted back to natural light after having been blindfolded during almost the entire kidnapping.
A couple days afterwards, Jimmy shows up at Tom's penthouse, requesting if he can claim the $4 million reward. Tom complies, and they go to his study where he begins to write out a check. As he does so, Jimmy then asks Tom a 'loaded' question: Why didn't he simply pay the ransom?
Tom explains it was because the kidnapper was 'human garbage,' and that in the end if push had come to shove, he probably would have paid 10 times the reward to get his son back.
As they talk, Sean wanders into Tom's eyeline off to the right, and upon seeing a bit of Jimmy's face and hearing his voice, a look of horror washes over Sean's face, and he urinates down the side of his pants. This causes Tom to recall that some news reports stated that they did not believe that Maris was the main kidnapper, and that she may have had an accomplice that escaped. Sean quietly leaves nearby, as Tom goes over and presents the check to Jimmy.
However, Jimmy (being an officer) noted Tom's hesitation, and now figures the businessman is on to him. Jimmy then demands that Tom call his bank and wire the $4 million directly to his account or he will kill him. However, Tom says that either Jimmy kills him now, or he can offer him another offer: they can go to his local bank and wire the money from there, after which Tom will allow Jimmy to be flown anywhere. Jimmy accepts this, but still threatens Tom that one day he very well could return to get his son again.
The two leave the apartment, and Tom makes a call on his car phone. However, calling under the pretense that he is making jet arrangements for Jimmy, Tom has actually contacted the Hawkins and his guys who are still in New York. Tom mentions that they'll be stopping by his bank before heading to the airport. Jimmy suspects that Tom may be attempting to double-cross him, but before he can turn the speaker-phone on, Tom has ended the call.
At the bank, Tom and Jimmy are greeted like royalty, and Tom wires the money through to Jimmy's account. However, as they leave the building, the FBI have tipped off the local Police about Jimmy, and several officers attempt to apprehend him. Jimmy then shoots two officers before darting into traffic. Tom quickly follows and attempts to subdue Jimmy. Eventually, the fight spills into the front of a storefront. Tom grabs Jimmy's gun and holds it towards him, just as Hawkins, some FBI agents and more NYC Police arrive. The Police threaten to fire on Tom and Hawkins demands that Tom put the gun down. Eventually, Tom lowers the gun, but Jimmy, though badly wounded, reaches for a spare in a holster on his leg. Before he can shoot Tom, Hawkins and several officers open fire on Jimmy, dropping him dead to the ground.
Kate soon after appears, and she and Tom walk off as the Police converge on the crime scene. Over the course of the beginning of the credits, we watch as the scene is cleaned up, and before evening arrives, the once violent scene has returned to normalcy on the street corner.