Slow Burn (2000)

Two Americans, with their young daughter Trina, live in the northern Mexican desert, searching for family diamonds lost years before. Jump ahead, Trina's parents are mysteriously dead, and Trina, now grown, continues the search against the advice of Frank, an old family friend. Two gringo convicts, recently escaped from the Matamoros prison and headed for Texas, stumble upon the diamonds then find Trina and ask her for a ride. She realizes they've found the diamonds, keeps that from them, and tries to spirit the diamonds away. Various alliances form and break, one of the convicts tries to convince her to abandon her quest, and Frank watches from a distance.