Every year, the monarch butterflies--las mariposas--fly more than two thousand miles on fragile wings to return to their winter home in Mexico. Now Luz Avila makes that same perilous journey south as she honors a vow to her beloved abuela--the grandmother who raised her--to return her ashes to her ancestral village. As Luz departs Milwaukee in a ramshackle old VW Bug, she finds her heart opened by a series of seemingly random encounters with remarkable women. In San Antonio, however, a startling revelation awaits: a reunion with a woman from her past. Together, the two cross into Mexico to await the returning monarchs in the little village Abuela called home, but they are also crossing a border that separates past from present . . . and truth from lies.