Hiram Abiff was busy working his Craft, when he suddenly found himself transported into the center of the Earth by Tubal-Cain, there to taste of the Tree of Knowledge. . . Who was the original ‘Widow’s Son’? That all depends on who you ask. This documentary explores a particular thread of Masonic history, namely the origin of the third degree, and the ‘lineage’ of the Craft. Sourced from some of the earliest manuscripts, and exploring certain facts not often brought to light, we shall see why the Mark of Tubal-Cain is an indelible stamp of heritage to the thoughtful Mason.