"The title character in 'Maria Full of Grace' is part of the international drug trade, but she's neither a user nor a gangster. She's a 17- year-old country girl from a poor family, and the money she will receive for swallowing rubber pellets filled with cocaine and flying to New York -- $5, 000 -- is three times the average yearly income in Colombia," G. Allen Johnson speaks with director Josh Marston and actress Catalina Sandino Moreno for the San Francisco Chronicle.