Engrossing, fast-paced modern thriller about the effects of a yet untested new drug called “NZT 48”, which boosts brain function from a supposed 20 percent to a full hundred. Bradley Cooper is mesmerizing in his first big leading role, showing considerable range in his transformation from scruffy writer wannabe to dapper, unnaturally smart executive. Cooper, along with Leslie Dixon’s fantastic screenplay and some sleek imagery are the reasons Limitless is such an exhilarating film. My only complaint: Morra (Cooper) going all vampiric on a Russian gangster (you’ll understand when you watch), a sequence that almost ruins the whole experience. Still, it’s one of the best films of the year in progress.