Jack Elgin is the European editor of The Economist, which is based in London, England. Jack has a wife named Maria and three kids named Joanne, Julia, and Andrew. Jack subtly changes the family vacation from a lazy week of Mediterranean fun and sun in Corfu, Greece, to a tour of India, because of a story he has to cover. Maria is not as impressed by this as the kids are. Jack himself envisioned a chance to simultaneously work an easy reporting assignment and spend a little quality time with his family. But on the way to India, the airplane, a 747 owned by AM Air, an American airline, makes an unscheduled stopover in Limassol Cyprus, because of a mechanical problem. After a while of waiting inside the Limassol airport, everyone gets back on the plane -- which is then hijacked by a group of terrorists known as the August 15th Movement, led by a Serbian man named Ivanic Loyvek and his right-hand man Karadan Maldic. The terrorists take a silver briefcase from an diplomatic courier, an older man, and it appears to be an important object of their hijack. And they are demanding $50,000,000 from the US State Department in one hour, or everyone on the airplane will die.
The demand is met, and Loyvek and Maldic start releasing the women and children, with the men to go last. But as soon as a front passenger door is opened, the local police begins shooting. Inside the plane, the owner of the briefcase retrieves it, only to be killed the terrorists, who take it again.The flight attendants frantically open the rest of the airplane's doors and start getting passengers out, but the terrorists start killing passengers, leading to an explosion. Maria, Joanne, and Julia get out of the airplane, and then Jack, holding Andrew, gets out -- only to watch Maria, Joanne, and Julia get shot by the terrorists. Jack tries to hide Andrew's face so he can't see. Maria and Joanne are killed, but Julia burns to death while crying for help.
Jack and Andrew survive. 15 passengers die, and Loyvek and Maldic, the surviving terrorists, escape, knowing that they now have the $50,000,000. Back in London, a devastated Jack is told that the terrorists were captured, but they were released and deported secretly, with no charges and no arrest, the result of some awfully compromised politics. Jack is understandably enraged that Loyvek and Maldic got off scot-free. While helping Andrew cope, Jack tries all the legal ways to ensure justice for his family, but to no avail.
Jack even pays a visit to Henry Davidson, a CIA agent who works at the American Embassy in London. Davidson tells Jack that there's little that can be done. The American and British governments are completely impotent when it comes to going after Loyvek and Maldic. Jack decides he has no choice in the matter but to seek revenge. With the help of his ex-intelligence operative friend Kate Stockton, who is well-schooled in the finer points of international intelligence, Jack becomes a one-man anti-terrorist squadron, searching for Loyvek and Maldich. He finds a warehouse they apparently are using as a headquarters. Breaking in, he finds some papers which he takes, and some weapons. The terrorists return, find a flashlight Jack was using, and begin searching the warehouse. Jack returns upstairs, retrieves a machine pistol and loads it with a magazine. He kills three terrorists before escaping.
He later breaks into the home of a friend at MI6 and steals a Walther PPK pistol from his home. He shows up at a theatre and makes a scene at the bar, to be sure he is noticed by the bartender. He then follows one of the terrorists in his taxicab, killing him with that weapon. He returns to the theatre and makes a point of apologizing to the bartender. The next day he goes pheasant hunting with his MI6 contact in case he is tested for gunpowder residue.
Dogging Jack's trail is FBI agent Jules Bernard, who's cooperating with Scotland Yard on anti-terrorist activities, and who suspects that Jack is the man who has been killing anyone involved in the hijacking. Jules tries to persuade Jack that he is on his side, and he's willing to help Jack make those responsible pay for the deaths of his family and the other people who died in Cyprus.
Bernard reveals that CIA agent Davidson who had been "assisting" Jack was behind the hijacking and has set Jack on a course to eliminate the terrorists so Davidson can keep the money for himself. The "August 15" name of the hijacking was a cover for purely financial motives. He tells Jack that he is now Davidson's target, and tells him into he has no choice but to help Bernard with bringing Davidson to justice.
Bernard tells Jack that Davidson intends to have him killed on a train bound for Paris where Jack is to cover a meeting of government ministers. Bernard accompanies him carrying a duffel bag full of grenades and automatic weapons. When Davidson's men attack Jack, Bernard and Jack shoot back, killing three attackers, including one of the hijackers.
In Paris, Davidson hijacks Jack and his driver, telling Jack the Bernard didn't have a warrant and all of the evidence he gathered is inadmissible. Jack swears at the driver, telling him he only needed 12 seconds to finish this. He jumps from the car, as does the driver. Davidson leans forward to grab the wheel and sees a grenade on the floor. The grenade explodes, destroying the car and killing Davidson.
Jack, his son, and Jack's friend Stockton depart on a sail boat, leaving behind Jack's workaholic life, his revenge complete.