What is the summary of journey of the sparrows?

"Nailed into a crate in the back of a truck, fifteen-year-old Mar?a, her older sister, Julia, their little brother, Oscar, and a boy named Tom's endure a terrifying and torturous journey across the U.S. border and then north to Chicago. There they struggle to find work-cleaning, sewing, washing dishes-always fearful of arrest and deportation back to the cruelties of El Salvador. By turns heartbreaking and hopeful, this moving story of the secret lives of immigrants is not to be missed.
A gripping, lyrical portrayal of a continuing American dilemma." ("Kirkus Reviews," pointer review)"