The source for the story is Plutarch's "Life of Marcus Antonius" in the translation made by Thomas North. Shakespeare worked closely from this translation, and an astonishing number of phrases within Shakespeare's play are taken directly from North's prose.
Though modern editions divide the play into the conventional five acts, Shakespeare articulated his drama in forty-two separate scenes, more than he used for any other play.
The play follows the relationship between Cleopatra and Marcus Antonius from the time of the Perusian War through to Cleopatra's suicide. The major antagonist is Octavius Caesar, one of Antony's fellow triumvirs and the future first emperor of Rome.
The role of Cleopatra in this play is universally considered one of Shakespeare's greatest female roles and one of the greatest female roles in world theatre.