The term 'Mario Puzo Best Seller' refers to the novel 'Omerta', written by Mario Puzo and published in 2000. It is a crime novel set in the United States and Italy, and follows the story of a Sicilian-American mobster who is trying to protect his family from the consequences of his criminal activities. The title of the novel, 'Omerta', is an Italian code of silence that is often associated with the Mafia.