Published in French by Jean-Jacques Pauvert, éditeur, it is a story of female submission about a beautiful Parisian fashion photographer, O, who is blindfolded, chained, whipped, branded, pierced, made to wear a mask, and taught to be constantly available for oral, vaginal, and anal intercourse. Despite her harsh treatment, O grants permission beforehand for everything that occurs, and her permission is constantly sought. While her friend and lover, Jacqueline, is repulsed by O's chains and scars, O herself is proud of her condition as a willing slave.
O's lover, René, brings her to the château of Roissy, where she is trained to serve the men of an elite group. After the training is finished, René hands O to Sir Stephen, an even more dominant master. O falls in love with him. As final proof of her love O decides to move to Samois, an old mansion solely inhabited by women for advanced training. There she agrees to receive a branding and a labia piercing with rings as a final sign of dedication to her lifestyle. At the climax, O appears as a slave, nude but for an owl-like mask, before a large party of guests.