The Three Musketeers is a novel by Alexandre Dumas. Set in the 17th century, it 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 being his friends Athos, Porthos and Aramis, inseparable friends who live by the motto "all for one, one for all", a motto which is first put forth by d'Artagnan.

In genre, The Three Musketeers is primarily a historical novel and adventure. However Dumas also frequently works into the plot various injustices, abuses and absurdities of the ancient regime, giving the novel an additional political aspect at a time when the debate in France between republicans and monarchists was still fierce