Set in the 17th century France, the novel recounts the adventures of a young man named d'Artagnan after he leaves home to travel to Paris, to join the Musketeers of the Guard. D'Artagnan is not one of the musketeers of the title; those are his friends Athos, Porthos and Aramis, inseparable friends who live by the motto: all for one, one for all (tous pour un, un pour tous), a motto which is first put forth by d'Artagnan.
