The heroine Clémentine Beauvais, a children author depressed by a series of literary and romantic failures, stumbles upon a curious historical enigma: who was the good fairy godmother of the little prince Louis XVII, son of Louis XVI and Marie-Antoinette? How could this fairy—endowed with powerful magical powers like all her colleagues of the time—abandon the little prince to an atrocious death? Even stranger, why did she disappear from the archives of history after the Revolution? And what if behind these mysteries lay the key to an even greater one: What happened the day the magic vanished?