It's taken kid-lit's pre-eminent sleuth nearly 70 years to make her celluloid comeback. Alas, even the brilliant bonce of Nancy herself would struggle to deduce why it all went wrong for this 21st-century update. The plot is cod-Agatha Christie, as the teenage 'tec (Emma Roberts) attempts to solve the suspicious death of a Hollywood actress whose dilapidated estate she's moved into. There's no mystery here; all but the most clueless viewer will clock the chief culprit the instant they appear onscreen. Neither Josh Flitter's chubby comic sidekick nor Max Thieriot's wet-weekend of a love interest provide suitable diversion; only the prim, poised Roberts sparkles, but her chops alone can't carry the film. The original books appeal to generations of readers, but this flick's strictly for tweens and slumming homage-spotters.