Edmond Dantès, Robert Donat is a capable young sailor whose bright future is suddenly threatened when his ship stops at Elba and a Napoleonic letter must be delivered to a contact in Marseille. Before the letter can reach its destination, the city magistrate, de Villefort Jr., Louis Calhern is tipped off by the scheming second officer, Danglars [Raymond Walburn], and Dantès is arrested after the exchange. Fernand Mondego, Sidney Blackmer accompanies him to the jail, but all three men—Mondego, Danglars, and de Villefort—stand to gain from keeping Dantès imprisoned: Mondego loves Dantès’ fiancée, Mercedes, Danglars seeks a promotion, and de Villefort’s own position is tied to the letter’s fate.
Dantès is condemned to the grim Château d'If, and eight years of solitary confinement follow. During this bleak period, he endures a slow, encoded education via the aged Abbé Faria, O. P. Heggie, a fellow prisoner who believes in a future beyond the wall. The two men become allies; Faria teaches Dantès, and together they plot escape. As their plans progress, Faria reveals a hidden treasure on a distant island, a fortune that could redefine Dantès’ life. When a cave-in fatally wounds the elder man, the dying mentor entrusts his wealth to his protégé and urges him to seize freedom. Dantès, now driven by a new purpose, substitutes himself for Faria’s corpse in the vault and is cast into the sea, where he eventually escapes and is rescued by a smuggling ship.
Following the clues left by Faria, Dantès uncovers the vast treasure on the desolate Monte Cristo and reinvents himself as the enigmatic Count of Monte Cristo. With wealth at his command, he hatches a carefully calibrated plan of revenge against those who betrayed him. He first targets Mondego, who had betrayed him to win Mercedes. To destroy Mondego, he engineers a grand display to reveal Mondego’s loyalty to Ali Pasha’s brutal defense, a tactic that lands Mondego in public disgrace. A dramatic duel follows between the two men; Dantès wins but spares Mondego, who, overwhelmed by shame, returns home and kills himself.
Next on the list is Danglars, now a powerful banker in Paris. Dantès manipulates Danglars by feeding him profitable tips that seem infallible, then watches as Danglars betrays others in greed. Danglars is bankrupted by a false tip he himself helped propagate, and Dantès reveals his true identity, leaving the once-formidable financier ruined and insane.
Albert Mondego—Mercedes and Mondego’s son—enters the drama, challenging the Count to a duel. Mercedes, recognizing Dantès, begs him not to kill Albert. Out of mercy, Dantès spares him, and Albert deliberately alters his aim to spare Mercedes from further heartbreak.
De Villefort, now a powerful State Attorney, becomes a central target as Dantès sends him information that exposes the Count’s true identity and his past misdeeds. De Villefort is arrested and tried; at first, Dantès refuses to testify to shield Valentine, de Villefort’s daughter who loves Albert. When Valentine learns of the danger, she encourages him to defend himself, and Dantès does so, presenting evidence of long-standing corruption that reaches into high places.
With all his enemies undone, the Count of Monte Cristo is finally reconciled with Mercedes, and the long road from vengeance to vindication comes to a close, leaving Dantès to confront what has become of the lives he touched along the way.
