In 1844, Alexandre Dumas published The Three Musketeers, a novel so famous and still so popular today that it scarcely needs introduction. Shortly thereafter he wrote a sequel, Twenty Years After, that resumed the adventures of his swashbuckling heroes. Later, toward the end of his career, Dumas wrote The Red Sphinx, another direct sequel to The Three Musketeers that begins, not twenty years later, but a mere twenty days afterward. The Red...