two tantalizing clues, a handprint. the subject had blood on their hand. and a trail on twitter. incredibly powerful. you can almost see this happening in realtime. could she help solve her own mystery? she s fighting him off. it was so emotional. i wanted to jump out of my seat. never in a million years would you expect something like that. on long island, about 10 miles down the shoreline from the mansions, the fancy cars and the elites of the hamptons, is a blue collar beach town some call the poor man s paradise. but life was rich for these brothers and sisters in mastic, new york, filled with the love of a large tight-knit family. all that was taken away one warm evening when evil rolled in with the summer tide. their youngest sister was missing. we just want you to come home safely. reporter: and for better or worse, this family would go to extraordinary lengths to find her. we re going to scour those woods right now. we were our own investigators.