I don't get it.
No, it's not that I don't get the film, it's that I don't get it that people can't follow the plot. Be warned, this post contains major spoilers.
Agent Jeremiah Ecks is an ex-FBI agent whose wife was killed seven years ago. He is approached by FBI Assistant Director Julio Martine, his former boss, to come back to the fold and do one more job. As bait, Martine tells Ecks that they've discovered his wife, Vinn, is still alive--but won't tell him where she is or how they found her.
The latest thing in assassination is a microscopic machine which, once insinuated into a target's bloodstream, can cause heart failure, embolism, whatever the hell it wants to--and it just looks like a natural death. The most advanced research facility for this technology is in Berlin--but the Berlin labs have recently been hit by a team of professionals, and the prototype(s) stolen.
Martine and the FBI believe Robert Gant is responsible. Gant is a high-ranking DIA (Defense Intelligence Agency) agent who, it is believed, is hoping to set up a shadow government. However, the only evidence they have is circumstantial (at best): one of Gant's lackeys was spotted in Berlin around the time of the raid. However, none of Gant's men, when they returned, were carrying the device. So where is it?
Added to that is the recent abduction of Gant's son by an unknown woman wearing a cloak and hood, captured on city security cameras. Michael has just returned from Europe. Martine believes there's something going on, and needs Ecks to investigate. Ecks, as a former profiler and with his unorthodox approach(es), is an excellent candidate for the job.
Cue shootout at the Vancouver Public Library. AJ Ross, Gant's lieutenant, is unable to capture the woman (who we learn is named Sever). Eventually, Sever escapes the clutches of the DIA, but not before shooting Martine (although not killing him), who tells Ecks that Sever knows where his wife is. Ecks pursues her to a rooftop, where he confronts her and demands to know where his wife is. A fight ensues and Sever escapes. Ecks goes back to temporary partner Harry Lee's place and does some research into Martine's files. He discovers Sever once had a family too--but that her infant and husband/partner were killed in an explosion at her house. We already know that Sever is an orphan-class operative--'bought' as a ward of the state from a Chinese family hoping for a boy under the one-child policy and then trained to become a lethal assassin. Ecks surmises that Gant had Sever's family liquidated as they presented a complication to Sever's work.
Ecks is subsequently arrested on suspicion of shooting Martine (no doubt influenced heavily by Ross and his DIA buddies). Ross interrogates him but learns little of value and so orders that Ecks be killed. Ecks is transported from the police station to...well, somewhere else...but a motorcycle-mounted Sever ambushes the prison bus with a grenade launcher. Ecks escapes and picks up a fallen motorcycle, pursuing Sever through Vancouver until he reaches a car wrecker's, where in a final confrontation Sever gains the upper hand, then reveals the location of Ecks' wife before letting him go.
Ecks follows his wife to the local aquarium/marine park thingy. She has been living the last seven years as Gant's wife. In a flashback, we see that, after a lunch together with Gant, Ecks was walking back to his car when it exploded. Vinn believed him killed. Gant hustled Vinn away, and then detonated his own car. Ecks believed Gant and Vinn had got into Gant's car, and so he believed both of them dead. So Vinn thought Ecks was dead, Ecks thought Vinn and Gant were dead. Now Vinn and Ecks have found each other again. They reunite and then decide to find Michael--who it turns out is actually Ecks' son, not Gant's. Upon leaving, Sever turns up. She is being pursued by DIA agents and ushers Ecks and Vinn into her car. Sever drives back to her hideout, shadowed by a DIA chopper all the way.
At Sever's silo hideout, Vinn and Michael reunite and Ecks is introduced to his son (although not as his father yet). Vinn and Michael hide at the top of the refitted silo in the service lift while Ecks and Sever prepare to meet the inevitable DIA assault head-on.
Cue firefight in the rail yard.
Ecks and Sever lay traps for Gant's men--and we discover that Gant was once FBI Agent Clark. Clark purportedly died when his car blew up, allowing Robert Gant to rise from the ashes and become one of the top-ranking DIA agents. The climax comes when Sever kills Ross, and then later kills Gant. She had taken the prototype from Michael's arm, where Gant had secreted it to get it back into the country, and placed it in a bullet. She fired the bullet at Gant's arm, the machines went into his bloodstream, and with the push of a button Sever activates them and ends Gant's life.
The end.
Now what the heck was so hard to follow about all of that? Really?