Tough and beautiful, Cary Fukunaga's Sin Nombre strikes such a stark contrast to last year's overhyped border-crossing drama Under the Same Moon that the two films - both addressing the experiences of Mexicans and Central Americans trying to get to the United States - might as well be from different planets.

Where Patricia Riggen shamelessly milked Under the Same Moon's melodrama, Fukunaga's startlingly impressive first feature is almost ruthless in its depiction of the brutality and degradation confronting the hidden hordes that cross rivers and hop trains trying to get to the United States.

Grounded in reportorial research and developed through the Sundance screenwriting lab, Sin Nombre ("without a name") tracks a teenage Honduran, Sayra (Paulina Gaitan), as she travels with her father and uncle through Guatemala and into Mexico, riding atop freight cars like the hoboes of the Great Depression.

At the same time, in Chiapas, in southern Mexico, a tattooed teenage gangbanger, Casper (Edgar Flores), has his own reasons for following the rails northward. The first jarring 15 minutes or so of Sin Nombre open a window onto Mexican gang culture, the violent initiation of a 12-year-old, and the casual murder of a girl.

And so Sayra and Casper meet - and it's not meet-cute, believe me. Their paths become inextricably linked.

Sin Nombre, shot in dazzling widescreen across sun-burnished landscapes and through colorfully run-down towns and cities, is forceful, heart-wrenching stuff. Gaitan and Flores deliver unnervingly natural performances - they don't ask for the audience's sympathy, they just present themselves, young, yearning, and in serious danger of not getting any older.EndText

Contact movie critic Steven Rea at 215-854-5629 or srea@phillynews.com. Read his blog, "On Movies Online," at http://go.philly.com/onmovies.