The film follows an ex-CIA "Preventer", who is faced with recovering his daughter after she is kidnapped by human trafficking|sex-traffickers in Paris, France.
Bryan (Liam Neeson), a former secret agent living in the US. He is skilled in hand to hand combat, divorced; and loves his 17-year-old daughter Kim (Maggie Grace) who lives with his ex-wife and her new husband Stuart (Xander Berkeley). Kim wants to take a vacation in Europe with her friend Amanda (Katie Cassidy), and together follow U2's European tour. Kim's mother allows this, but Kim also needs permission from her father. Since Kim fears that Bryan will not consent, she pretends that they will only stay in Paris. Reluctantly, Bryan agrees.
In Paris a seemingly friendly young man named Peter (Nicolas Giraud) proposes to share a taxi with them to the house where Kim and her friend are staying, and so they do. However, the man works for an Albanian Mafia|Albanian criminal organization, to which he reports the address.
In the house, after a few minutes Kim receives a phone call from her father, where she then goes to the bathroom. She then sees from the bathroom window, men entering the room and abducting Amanda. Bryan is able to gain critical information about the kidnappers in the final moments after Kim is kidnapped by telling her to shout out everything about them that she notices. Briefly Bryan talks to one of the kidnappers, telling him that if they let his daughter go he will not pursue them, before the man smashes his daughters phone.
Using his contacts in the CIA and the business connections of his ex-wifes husband, Bryan travels to Paris to find her, informed that the kidnappers are sex-slavers and that he has only 96 hours to recover his daughter before she will disappear forever. The particular kidnapper he talked is revealed to be an Albanian named Marco.
Under the eye of Jean-Claude, himself a former operative and now deputy director of Internal Security, Bryan locates the kidnappers, first by using the digitial photos off the smashed remains of Kims phone to locate Peter who is later killed while Bryan pursues him. By hassling prostitutes Bryan is threatened by an Albanian mobster and is able to plant a covert listening device on him. Using a translator he finds that the kidnappers have a brothel in a nearby construction site.
Once arriving, Bryan acts like a customer, and after making his way inside begins to search for Kim. Unfortunately, he only finds her jacket, on another woman. He then is discovered and has to escape with the girl.
Nursing the girl back to health from an involuntary drug addiction, Bryan finds out where the kidnappers took her after she was abducted. Bryan heads to the address, and though he doesn't find Kim, he does find Marco, subduing him and killing most of the kidnappers. He searches for Kim, but instead finds Amanda, handcuffed to a bed and dead due to a heroin overdose. Torturing Marco, Bryan is able to ascertain that Kim was sold to a man named Saint Clair.
Bryan visits Jean-Claude's home and its dinner time there. However Jean, failing to have Bryan arrested for the mess he has caused at Paris, carries his gun to the dinner table. Jean angrily points the gun at Bryan when accused of complicity in his daughters abduction. Bryan has already unloaded the gun and shoots Jean's wife on her arm and, holding Jean, discovers the location of Saint Clair from him.
Acting as a police officer he gains entry to the building where new girls are being sold. When he sees his daughter being sold, he forces one of the buyers to purchase her, but is captured and knocked unconscious moments later. Suspended from the ceiling, Saint Clair questions his identity before leaving his security guards to execute him. Bryan escapes and kills them before finding Saint Clair, murdering him after learning that his daughter is being taken by Arab clients. Bryan manages to track down the car his daughter is being taken in and finds out that she is taken away on a large motorboat. He jumps on to the ship from a bridge and eliminates all the people inside, finally freeing his daughter.
Back in the US, Kim is reunited with her mother. Bryan introduces her to a pop Diva (Holly Valance) whom he saved at the beginning of the film from a knife attack while working security, Kim having an audition with the Divas vocal coach.