The book: an epic arch sinfulness, The Holy Sinner is one of Thomas Mann's great works. From the incestuous union of the two beautiful children of the duke grimald of flanders a boy is born. Left to die at sea, the child...The book: an epic arch sinfulness, The Holy Sinner is one of Thomas Mann's great works. From the incestuous union of the two beautiful children of the duke grimald of flanders a boy is born. Left to die at sea, the child is eventually rescued & brought up in holiness on the channel islands.