According to production notes, Thunder Knocking at the Door is set in 1966 rural Alabama and is the story of "the Dupree family, whose lives are turned upside down by the arrival of Marvell Thunder, a mysterious stranger with amazing powers. A devilish charmer, Marvell challenges Glory, the Duprees' blind daughter, to a blues guitar 'cutting contest.' At stake are her family's musical legacy — both past and future — her sight, and perhaps her best chance at love."
— By Christine Ehren