Zero Hour is a documentary-style television series. It aired on History Television in Canada, on the BBC in the United Kingdom, and on The History Channel in the United States. Zero Hour has also aired on Channel Seven in Australia (third series aired on Network Ten from 1 May 2010 and now plays on 7mate); on Discovery Channel in Africa, Asia, New Zealand, Brazil, and the Netherlands. The program focuses on retelling the details of tragic man-made disasters which each unfolded in less than an hour. Three narrators were used over the three seasons, David Morrissey, Paul McGann and Sean Pertwee.