Stunt man Nik Wallenda will attempt to walk across Niagara Falls 173 feet high on a wire. He will attempt this death defying feat live June 15th 8pm ET on ABC.  His family makes a career out of high wire walking. His grandfather died during a high wire walking attempt, but that hasn't slowed Nik down. Nik is looking to enter the Guinness book of world records with this next attemp.