In the last 40 years, Mexico City, one of the largest and most densely inhabited places in the world, has seen a population explosion from 1 million to nearly 20 million. The landless peasants who arrive in Mexico City find survival no easier than the rural poverty they sought to escape. Half of Mexico City's people are, or have been, illegal squatters.

By introducing us to several families who struggle to survive here, the film puts a human face on Mexico's urban poor. The Martinez family is one of 37 families who live in the shell of a house reduced to rubble by an earthquake. Ramon Martinez dreams of saving enough money from his shoe shine work to marry the mother of his four children in a proper ceremony. Guadalupe is a single mother living in one of the tin and cardboard shacks that lines the road to the airport. She shares a tap of untreated water with her neighbors. Jorge is one of 20,000 people who live on the fringe of Mexico City's garbage dump. His wife was buried alive by an avalanche caused by the illegal dumping of trash.

One organizer, Clara Brugada, is part of a barrio which decided to fight back against poverty. With their own hands the people replaced the mud huts with sturdy housing and stood up to the police who have tried to evict them. It now stands as a beacon of hope for the millions who live on the edge.