Overview: A man (Liam Neeson) wakes up from a coma while on a business trip to Europe only to find that some other man has taken his identity and stepped into his life. Diane Kruger and January Jones co-star.

Verdict: "Unknown” is based on a 2003 French novel by Didier van Cauwelaert, published in English as “Out of My Head,” though its truer inspirations are those films noirs of the 1940s and ’50s in which an Everyman wakes up with a lump on his head and asks the great essential question, Who am I?

That same existential cry fuels the first “Bourne” movie (2002), which “Unknown” apes in large and small ways, from its international setting to its friendly, tag-along Euro-chick; conspiratorial web; and paranoia. Yet despite its A-movie aspirations, as the chases continue and the plot holes widen, “Unknown” quickly settles into the familiar B-movie comfort zone, with mano-a-mano fights, missed phone calls, running and more running and a twist that keeps twisting until it breaks.

Liam Neeson’s latter-day renaissance as an unlikely action star should give hope to performers and viewers of a certain age (i.e., over 40) everywhere. While that irrepressible exhibitionist Helen Mirren, born in 1945, continues to inspire legions of AARP members, one discarded garment at a time, Mr. Neeson, a comparative pup born in 1952, is doing much the same, one hard-swinging fist after another.

And so here he is again, racing against time and villainy, this time in “Unknown,” another sleek, preposterously amusing thriller with a single-word title. Like “Taken,” his surprise 2008 hit, this new movie largely banks on the spectacle of Mr. Neeson’s character — here, a botanist, Dr. Martin Harris — pursuing a much younger woman.