We live in an age where it’s almost impossible to get truly lost. Between GPS systems, the ever-growing presence of surveillance cameras, the ability to track credit-card purchases instantly around the globe, and cell-phones that can connect us via calls and texts to nearly anyplace in the civilized world, a person can feel pretty confident that they can’t ever truly lose contact with loved ones in a time of need.

But what if that sense of security suddenly disappears? And even worse, what if you can’t remember all the things that are important to you, and those around you are claiming they don’t know you either?

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That is the harrowing dilemma at the heart of the terrific new thriller “Unknown,” a film that updates classic Hitchcock thrillers like “The Man Who Knew Too Much” to the modern world but still relies on timeless foundations of solid performances, inventive writing, perfectly moody atmosphere and a reality-based sense of location that makes every moment feel all too real. And at its core is the essential idea of an Everyman who is thrust into a terrible situation and must find the inner strength and cleverness to find his way back out.

Following Dr. Martin Harris (Liam Neeson) and his wife Elizabeth (January Jones) as they go to Berlin for an important botany conference, Martin quickly finds he has to race back to the airport after forgetting a vital briefcase with classified information. He goes back so quickly that even his wife doesn’t know where he went, and when he suffers a four-day coma after a taxi accident, Martin finds that his wife claims she doesn’t know him, another man (Aidan Quinn) is claiming to be him, and that he can’t even remember what secrets he was bringing to the conference himself. He turns to his cab driver (Diane Kruger) and a former East German secret policeman to help him figure out the mystery, one that spirals ever more complexly through a series of shocking twists.

“Unknown” marks the second foray into action-hero status for Neeson after the slam-bang thriller “Taken” in 2009, and he again fits the role well. “Unknown” is an even better – if less wildly entertaining – film because its more complex story stays mostly in the realm of plausibility, and because the performances and writing of the characters across the board are three-dimensional.

Director Juame Collet-Sera does a superb job building a low-boil tension to heightened levels at key moments in the film, while he and screenwriters Oliver Butcher and Stephen Cornwell masterfully use amnesia and the stranger-in-a-strange-land motif to keep both Martin and the audience on their toes for the entire running time. Their vision of Berlin as cold, grey and utterly baffling to an American man with no knowledge of German sets the film in a netherworld that has a constant sense of dread, and their detailed side story of Kruger’s plight and hope for a better life is uncommonly affecting for a thriller.

All told, “Unknown” is a rare modern thriller that takes its time to unspool its story and keeps viewers hanging on for the ride right alongside their hero. Let it be known that this is one film well worth seeing.