An introduction to Twenty Years After is provided by A. M. de Medeiros of the University of Kent at Canterbury. After "The Three Musketeers" came out, Alexandre Dumas wrote a follow-up novel that was just as good as the first one in every way. The adored D'Artaganan, Athos, Porthos, and Aramis return in "Twenty Years After" to battle the forces of evil. They overcame the tough opponent Milady in the first book; now they must battle her vengeful son Mordaunt and thwart the schemes of the evil Cardinal Mazarin. Their exploits also led them to England, where Charles I is set to be overthrown by Cromwell. They must face the challenges that time has put in their way while this is happening.