A single mother of a leukemia-stricken child is redeemed by the titular positive force in Paco Torres’ intriguing debut, “The Magic of Hope.” Starting out as a po-faced tale of endurance, pic develops into a convincing, quietly affirmative fable about the transformative power of human goodness. Featuring a searching central performance from Patricia Garcia Mendez and employing a distinctive mix of grit and lyricism working in mutually beneficial counterpoint, pic is far from perfect, but its seriousness of purpose and undertow of emotional truth could be met with applause by fest auds.