The Three Musketeers is a classic novel by Alexandre Dumas, first published in 1844. It's a swashbuckling tale set in 17th-century France and follows the adventures of a young man named d'Artagnan as he befriends three musketeers, Athos, Porthos, and Aramis. Together they fight for justice, defend the honor of the king and queen, and get into all sorts of thrilling escapades.