The Three Musketeers, Alexandre Dumas's most famous and enduring novel, completed its serial publication in the summer of 1844, and by the time of its book publication at the end of that year readers were already demanding a sequel. They got it starting in January, 1845, when the first chapters of Twenty Years After began to appear-but it wasn't quite what they were expecting. When Twenty Years After opens it is 1648: the Red Sphinx, Cardinal Richelieu,...