braver will be telling us about in our sunday morning cover story. reporter: the feud that began this delete s in the 1860s between hatfield and mccoy is itself an american legend. and no wonder. you ve got these amazing characters doing the unbelievable things on a shakespearean scale. you ve got love stories, murders, the civil war. it s got everything. reporter: later on sunday morning, the real story behind what may be the most notorious feud in american history. osgood: whatever your family name, you re likely to find a certain island strictly off limits unless you ve got official permission to go there. our john miller got that permission and went there. reporter: for decades, there have been rumors about what really happened on new york s plumb island. i cannot comment on our list of inventories that are sensitive information. reporter: we get a rare glimpse, a trip to the government s secret island ahead on sunday morning. osgood: charlize theron has p