'Same Moon,' Seen From Cloud Nine

She saw Riggen's work at a student film festival, "and I thought it was extraordinary," Villalobos says. As she would witness on the set of "Moon," "One of Patricia's strengths is the ability to communicate with actors in a way that allows them to come up with the best performance that they have."

Both women thought the story touched universal emotional issues while set in a border-crossing context. At the time, three years ago, immigration wasn't the hot topic it is today.

Back to Riggen: "What I saw immediately was the love story," she says. "The love story between a mother and a child."

The film portrays an incredible week in the life of the boy, Carlitos (Adrian Alonso), and his mother, Rosario (Kate del Castillo). Riggen weaves scenes of Carlitos in Mexico, and his adventures on the road, with Rosario's struggles in L.A. Rosario is unaware that Carlitos sets out to find her. A gruff older migrant, Enrique (Eugenio Derbez), reluctantly takes the boy under his wing. The premise is not as improbable as it may seem; in 2005, the U.S. Border Patrol apprehended 115,000 unaccompanied minors.

Riggen worked hard to get right little details about daily life as an illegal immigrant. And she highlights the existential dilemma of immigrants in Rosario's position: The act of leaving her boy behind to make his life better may simultaneously have the opposite consequence. Carlitos begins to question his mother's love; Rosario questions whether the sacrifice is worth it.

"I say I am not political because I am not trying to convince people of any particular idea," Riggen says. "I am just trying to be very true to these characters, and to their dilemmas."

Part of the truth lies in the cultural touchstones of undocumented life that she puts in the film. Hitchhiking, Carlitos and Enrique hop in a van filled with guys with guitars and accordions: It's Los Tigres, on tour. Riggen wanted the band in the film because it is so hugely popular with Latino immigrants and because its main subject is immigrant life.

Now, by telephone, it's Tigres leader Jorge Hernandez: "One day I was in Mexico and I got a phone call that Patricia wants to meet me," he says. "She says, 'One thing I have to make clear to you: I have no money.'

"I said, 'That's okay. I like the story.' "

In a charming scene, the band sings the soundtrack song for Carlitos and Enrique.

Similarly, Ferrera's small role captures another piece of the reality. She plays a second- or third-generation Chicana, an American citizen, who can't speak Spanish but resorts to smuggling to pay for college tuition. "Crossing the border and getting a visa is not enough," Riggen says. "There's an ongoing struggle."

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