When a mission to retrieve a stolen suitcase bomb goes bad, CIA agent Kevin Pope (Chris Rock) is killed. Pope was working undercover as an antiquities dealer under the name Michael Turner. The CIA, who is desperate to complete the mission discovers that Agent Pope had a twin brother, Jake Hayes (also Rock), from whom he was separated at birth; their mother died giving birth and Hayes suffered from a severe lung infection that prompted the doctors to separate them because they felt that Hayes was unlikely to live for very long. Hayes hustles chess games, scalps tickets and works at small clubs in Jersey City to make ends meet. Meanwhile Hayes's girlfriend, Julie (Washington) grows tired of waiting for him to grow up and decides to move to Seattle, Washington.After the CIA successfully persuades Hayes into participating and begins to train Hayes for a mission that is to take place in Prague (Czech Republic), they are initially dismayed by his lack of refinement. Agent Oakes (Anthony Hopkins) confronts Hayes telling him he doesn't trust him. When Hayes begins paying attention, the CIA sets him up in his brother's old apartment in Manhattan to test him and try to bait the men who killed his brother. Hayes is attacked, but escapes unharmed. Looking for a way out, Hayes goes to his foster mother only to be found by Oakes who persuades him to finish the mission.After arriving in Prague, Hayes meets with the men selling the suitcase bomb posing as his dead brother. The seller, Adrik Vas, is an ex-Russian Army Colonel with ties to the Russian Mafia. When they return to their hotel, Hayes is greeted by his brother's ex-girlfriend Nicole. Believing that Hayes is his brother the two have dinner and return to the hotel only to be ambushed by rival buyers. Nicole figures out Hayes isn't his brother and returns to her assignment covering the Balkans for CNN.Moving forward with the plans, Hayes and Oakes meet up with Adjanic and are able to steal the arming codes. Just as they close the deal, Vas' men double cross him with the rival buyer. When the rival dealers, who are part of a Greek terrorist organization, learn they can't detonate the bomb because of the missing codes, they kidnap Julie. Hayes gives himself up trying to save his girlfriend and the terrorists get the codes back and arm the bomb.Now the race begins to find Hayes and the bomb. After interrogating one of the captured terrorists, they track the bomb to Grand Central Station. With the clock ticking, they locate the bomb and Andre who has started the countdown. Oakes rescues Hayes by killing two terrorists. As Hayes starts to enter the codes to disarm the bomb, Andre holds Julie hostage. In order to distract Andre, Hayes pretends to shoot Oakes and they kill Andre by shooting him repeatedly. Hayes is able to disarm the bomb just prior to detonation.At the ending of the film, Hayes visits the memorial for deceased secret agents to visit his brother's grave. Later on, Oakes comes up to Hayes at Hayes's wedding and warns him that a dangerous criminal has escaped from prison and is seeking revenge upon Kevin Pope, but since Kevin is dead and Hayes was impersonating him, the criminal thinks Hayes is Kevin. Hayes begins to panic and demand that Oakes has to protect him, but Oakes starts laughing as he reveals that it was just a joke and he really just came for the wedding.