What is it about the tropes of classic film noir that are so reliably pleasurable? In real life, there'd be nothing particularly appealing about meeting a sleazy private dick with a mean sense of humour and an early-morning booze habit; but place that archetype in a dimly-lit film with a smoky sax on the soundtrack, and he can stir a nostalgic glow to which few movie buffs are immune. The frequent revival of noir trappings by hip young directors certainly constitutes grateful homage to early influences, but it also provides a useful means for them to pass social comment without sacrificing cynical wit or stylistic flair. Film noir has by convention served as a sort of receptacle for moral and political anxieties; the morose gumshoe stands slightly outside whatever ethical murk surrounds him, and yet is susceptible to it and soiled by it himself, making him an acceptable anti-hero for viewers not keen on being preached at. Thus Rian Johnson's high school noir Brick (2005) could address teenage violence without being pigeonholed as a tragic Columbine commentary, and Noah Buschel's The Missing Person can consider the psychic fallout from 9/11 without resorting to mawkish clichés about Ordinary Heroes and American Values. Our tough-talking protagonist here is John Rosow (Michael Shannon, a recent Oscar®-nominee for Sam Mendes' Revolutionary Road). Initially, there's no indication that John's new case has anything to do with the demise of the Twin Towers: he thinks he's tracking a paedophile who's attempting to smuggle an underage kid to Mexico. The plot thickens considerably, however, as Rosow finds out more about his mark – and discovers disturbing echoes of his own recent past. Buschel's film doesn't stint on the big themes – loneliness, loss, post-traumatic stress and the effort to force goodness into a wicked world – but this skilled young writer/director leavens the mix with surreal humour, exquisitely witty dialogue and neat inversions of our expectations. Shannon, meanwhile, shows here that he's a major leading man waiting to happen. Playing a character who seems transposed from somewhere circa 1946 (he's baffled by cameraphones and California's anti-smoking laws), he's at once craggy, cool and endearingly naïve; we're wholly with this character even before we learn the tragic secret that made him how he is.