What is the author's style in Twenty Years After by Alexandre Dumas?

This story is told from a third-person point of view. The narrator who tells the story is not included in the action of the book. Although there is a strong focus on d'Artagnan in the novel, as he is one of the main characters, the story is not told from his point of view nor does the writer focus solely on d'Artagnan. The narrator shares the actions of the characters of the novel, but does not delve much into the emotions and inner thoughts of the characters.