Liam Neeson is the actor you automatically associate with action movies and general bad assery. Unknown, directed by Jaume Collet-Serra, is merely an addition to Neeson's distinctiveness in the genre of intrigue. On a trip to Berlin with his wife, Liz (the one-trick pony we call January Jones), Dr. Martin Harris has the misfortune of getting into a car accident while taking a cab back to the airport to retrieve a briefcase containing all of his personal documentation.
In one of those life-fucking up events, Harris' cab driver, an illegal immigrant named Gina (Diane Kruger), crashes the car and sends the two flying over a bridge before he can make it back to the Berlin Airport. Gina flees the motherfucking scene (because what illegal immigrant wants to deal with talking to the police, let alone a legitimate citizen?) as soon as she busts the window open to let an unconscious Harris float to the surface.
Liam Neeson, composed and dispassionate when it comes to expressing emotion through any of his characters, awakens in a hospital after four days of being in a coma--exhibiting far more equanimity than any normal person would upon learning not only this information, but that he is in the care of German medical professionals. Harris' first order of business is, of course, finding his wife.
When Liz re-encounters her husband at the biotechnology conference he was slated to speak at, she acts as though she has no recollection of their union, chiefly because she claims to be married to "the real" Martin Harris (played by Aidan Quinn, who looks nothing like the version of himself that exists within the frames of Desperately Seeking Susan). This sends Neeson's Harris on a rogue quest to reclaim his identity, searching for Gina first and foremost, being that he knows she will be the only person willing to admit to recalling him.
At the outset, Gina is extremely resilient to the idea of helping him, but eventually comes around when she sees how absolutely desperate he is, even going so far as to hire a former member of the Stasi (what is it with Sebastian Koch being in Stasi-related movies, namely Das Leben Der Anderen?). And, as Gina becomes more invested in learning the true ipseity of Martin Harris, she finds that, reckonably, her feelings for him are becoming more than just platonic.
As the film progresses, the audience will still have difficulty discerning how all of this is possible until the denouement. True to Liam Neeson's form of script selection, the plot twist in Unknown is not quite what one would expect, but don't give screenwriters Oliver Butcher and Stephen Cornwell too much credit as the book is based on a novel by Didier Van Cauwelaert called Out of my Head.