The Count of Monte Cristo is a serialised adventure novel by Alexandre Dumas Père, published in the Journal des Debats from August 1844 to January 1846, based loosely on an allegedly true story which Dumas discovered in a collection of police reports.
Edmond Dantès is a guileless sailor experiencing a run of good luck: he has just been made captain of his ship, and is newly engaged to the beautiful Mercédès. On his wedding day, Fernand Mondego (Mercédès' cousin and Dantès' rival for her affections) and Danglars (Dantès' co-worker, who is jealous of the former's rise to captain) decide to frame Dantès by sending an anonymous letter fingering him as a Napoleonic spy. Dantès is arrested and brought to crown prosecutor Gerard de Villefort, who is initially sympathetic to Dantès until he finds a letter in his possession that would expose Villefort's father as a leader in a Neo-Bonapartist conspiracy. Taking no chances, he destroys the evidence of Dantès' innocence and fast-tracks him to the Chateau d'If, a hellhole prison for enemies of the state.
During his stretch, Edmond meets and befriends a fellow lifer, Abbe Faria. Faria educates him in a variety of subjects; helps him piece together the truth about his imprisonment; and before dying, tells of a treasure of unthinkable magnitude buried on the island of Monte Cristo. Edmond manages to escape by smuggling himself inside Faria's bodybag, and claims the treasure.
He returns to France as the brooding, cultivated, and no-named Count of Monte Cristo. He discovers that Mondego, Danglars and Villefort have all become rich and powerful—Mondego is now the Count de Morcerf, and a war hero; Danglars is now a baron, and head of a bank; and Villefort is now one of the most prominent lawyers in Paris—and sets about using their evil pasts and tainted passions to enact an elaborate and cruel revenge. A complication arises in that their children are, by and large, genuinely good people whom the Count numbers among his few friends.
For a list of adaptations or works inspired by the novel, see here.