This is one of those all time great books. It’s been made into a movie several times and brings with it that immortal phrase “all for one, one for all” (“tous pour un, un pour tous”). It was originally published in serial form in 1844 and by 1846 had been translated into three different English versions. Many of explicit and implicit references to sexuality had been excised. I believe the most recent translation by Richard Pevear (2006) has corrected most of those and makes it easier to understand the relationship between d’Artagnan and Milady.
The story of d’Artagnan is continued in Twenty Years After and The Vicomte of Bragelonne: Ten Years Later. Those three novels by Dumas are together known as the d’Artagnan Romances.