Les Liaisons dangereuses (The Dangerous Liaisons) is a French epistolary novel by Choderlos de Laclos, first published in four volumes by Durand Neveu from March 23, 1782.
It is the story of the Marquise de Merteuil and the Vicomte de Valmont, two rivals (and ex-lovers) who use sex as a weapon to humiliate and degrade others, all the while enjoying their cruel games. It has been claimed to depict the decadence of the French aristocracy shortly before the French Revolution, thereby exposing the perversions of the so-called Ancien Régime. However, it has also been described as a vague, amoral story.
As an epistolary novel, the book is composed entirely of letters written by the various characters to each other. In particular, the letters between Valmont and the Marquise drive the plot, with those of other characters serving as illustrations to give the story its depth.
It is often claimed to be the source of the saying "Revenge is a dish best served cold", a paraphrased translation of "La vengeance est un plat qui se mange froid" (more literally, "Revenge is a dish that is eaten cold"). However the expression does not actually occur in the original novel in any form.
Read more about Les Liaisons Dangereuses: Plot Summary, Literary Significance and Criticism