Bradley Cooper (The Hangover) is introduced to a miracle drug called NZT that expands his mind to Stephen Hawking-like levels. But what happens when the drug wears off? Can you imagine coming down from something like that? And what you would do to get more of it? Those questions come into play, although the ways they’re spun into the story are the least-rewarding aspects of the film. Director Neil Burger (The Illusionist) gets good supporting work out of Robert De Niro and Abbie Cornish, but this is mostly Cooper’s showcase, and there’s no reason to believe he won’t keep adding leading roles to his résumé. The problems with Limitless have nothing to do with him, and he’s the one whipping this horse to go farther, faster. Most of the time, it does just that.