Be warned: Within its first few minutes, "Under the Same Moon" will reach out, grab your heart and squeeze, hard. This often wrenchingly moving film -- about a 9-year-old boy searching for his mother across the U.S.-Mexico border -- exerts immediate, irresistible power, combining an affecting story, indelible characters, urgent topical relevance and superbly calibrated sentimentality. As this absorbing story wends through the harrowing realities of modern-day immigration, the audience's only recourse is to hope ever more fervently that "Under the Same Moon" won't break the hearts it has so swiftly and thoroughly captured.

Thanks to the uncommonly shrewd judgment of screenwriter Ligiah Villalobos and director Patricia Riggen, both newcomers, the film never feels like rank exploitation, even as it steadily aims for the emotional jugular. They keep their story gratifyingly simple: Rosario (Kate del Castillo) has been living in Los Angeles for five years, working as a maid and sending money back to her son, Carlitos (Adrian Alonso), who lives with his grandmother in Mexico. A sudden turn of events inspires the resourceful Carlitos to travel to California to find Rosario, even though he possesses only a mailing address and a vague notion of where she calls him every week from a pay phone. The film follows him for an event-filled week during which he illegally crosses the border and along the way encounters a series of strangers who aid, abet and betray him.

Deftly cutting between Carlitos's journey and Rosario's life in L.A., the filmmakers present a vivid, almost palpable image of the lives of undocumented workers who sacrifice everything to escape grinding poverty and offer their children something more. "No one chooses to live this way without a good reason," observes one of Carlitos's traveling companions. That simple truth takes on unforgettable life in a story that traverses tense border checkpoints, chemical-laden tomato farms, restaurant kitchens and L.A.'s faceless, imposing metropolis.

The tone never succumbs to unremitting grimness. Instead, the filmmakers regularly leaven their story with little unexpected grace notes of humor and tender irony.

The fact that "Under the Same Moon" has been crafted with such an adroit, sensitive touch should reassure viewers that, as it approaches its utterly gripping climax, their hearts are in good hands, too.

-- Ann Hornaday (March 21, 2008)

Contains mature themes. In Spanish with subtitles.