During the late 17th and early 18th centuries, two violinmakers from the same small town, indeed, the same block, were making the most sought-after violins ever created. Everyone has heard of Antonio Stradivari, but few know the name Giuseppe Guarneri del Gesù. Through interviews with historians, experts, luthiers, and virtuosos, this documentary tells the story of these two masters of violinmaking and why today their stringed instruments are worth millions of dollars to musicians and collectors the world over.