The mystery of the Iron Mask - a mysterious prisoner of the Bastille, who, on pain of death, was forbidden to show his face to anyone and tell his true name - has haunted historians, novelists and simply history buffs for more than three centuries. Serious studies and frivolous novels, plays and films were dedicated to him. By the will of the great Dumas, he was freed from captivity by the musketeers, led by the inimitable d'Artagnan; his image is imprinted in our memory thanks to the magnificent films in which Douglas Fairbanks, Jean Marais and (in the newest film version of “The Man in the Iron Mask”) Leonardo DiCaprio shone at different times... The book offered to the attention of readers today represents the most complete and an authoritative examination of this historical mystery. The author gives his answer to the question of who the mysterious prisoner was. And this answer turns out to be very unexpected: the person we are accustomed to from novels and films is just a myth that has nothing to do with reality. At the same time, the book is structured like an exciting detective story: it has everything - a painstaking investigation carried out three hundred years after the death of the prisoner, and a thorough analysis of the evidence, and checking the alibi of each suspect for the role of the Iron Mask, and false versions, numerously placed by the story itself and cunning French jailers.