One July morning in 2007, 19-year-old Brian Sullivan made some calls to a friend, grabbed a hot breakfast from a local fast-food joint, then vanished, never to be seen or heard from again. For 15 years, Brian’s disappearance has haunted the greater Rochester, New York, area — and although investigators know beyond a reasonable doubt who was responsible, they haven’t been able to answer the one question left looming over their heads: where is Brian?