Nine years after the murders of his pregnant wife and two young daughters, the guilt of Green Beret Dr. Jeffrey MacDonald is put to a civilian jury. The defense calls a surprise witness: The Girl in a Floppy Hat.

Joe McGinniss' book, "Fatal Vision" paints a not-so-flattering picture of Jeffrey MacDonald, but new evidence may prove that MacDonald is innocent.

Jeffrey MacDonald served more than 30 years in prison when a federal judge finally agrees to hear the new evidence in his case. Errol Morris heads to North Carolina believing the truth will finally come out.