Before setting pen to paper, Sin Nombre writer-director Cary Joji Fukunaga purportedly rode the rails in the company of real illegal immigrants traveling from Mexico to the U.S. But from the looks of it, he spent even more time studying Brazilian director Fernando Meirelles’s slicked-up slum porn City of God: diminutive kids with guns-check; carefully lit and art-directed shantytowns-check; doomed teen romance-yep, that too. In fairness, Fukunaga’s film isn’t quite as ostentatiously vulgar as Meirelles’s: Its loftier aspirations are obvious from the opening shot of El Casper (Edgar Flores), a young initiate in the fact-based Mara Salvatrucha gang, staring fixedly at a photo enlargement of a leafy wooded landscape-a signal flare (along with his teardrop tattoo) that he’s really a soulful poet-dreamer trapped in a violent existence. After his girlfriend is raped and murdered by the gang’s more elaborately tattooed leader, Casper makes a break for it, hopping the same U.S.-bound freight train on which Honduran teen Sayra (Paulina Gaitan) and her father are heading to the promised land. Meanwhile, Casper’s best friend, Smiley (pint-sized Kristian Ferrer), is dispatched to track the fugitive down-hmmm, do you think these two amigos will find their personal loyalty tested by obeisance to La Mara? Lushly photographed and meticulously sound-designed, Sin Nombre is visceral without being vital, researched without ever seeming lived-in. The best that can be said is that it’s a more honest film on the subject of immigration than the recent Crossing Over-but then again, so is Beverly Hills Chihuahua.