In September 1982, the Investor - a state-of-the-art salmon boat - was found drifting and engulfed in flames just off the coast of Fish Egg Island, Alaska. What the Coast Guard found in the embers was a nightmare: the remains of Mark and Irene Coulthurst, their two young children, and four teenage deckhands. It remains one of the worst mass homicides in Alaskan history. So who did it? Why did they do it? And where are they now?