Dumas creates a gripping, suspenseful mood for the reader, fueled by the pain of Dantès's wrongful accusation and the satisfaction of a lengthy tale of revenge. To sustain this mood across more than a thousand pages, Dumas relies on action sequences of swashbuckling, violence, and, in some cases, poisoning—woven together with a healthy bit of Romance, some lighthearted adventuring, and satire of 19th century French society.
Above all, however, Dumas stokes suspense through the regular use of dramatic irony. Because the Count of Monte Cristo goes by a great many different names, and because much of his revenge plot hinges on his hidden identity and cunning sense of trickery, the novel is set up from the very start to maximize dramatic irony for the reader. Often, it is only the reader who will be able to see through the subtext of the Count's dialogue as he plays with his unsuspecting victims, and it is only in the final sections of the novel that the reader's patience is finally rewarded with dramatic reveals of the Count's true identity and ambitions.
There is also a consistent sense of grandeur in the Count's actions, fueled by his sense of purpose and fervent belief in his noble—and perhaps even heaven-sent—cause. This grandiosity, combined with the epic scale of the novel, combine to create a triumphant mood by the end of the story.