Almost three tonnes of ammonium nitrate was somehow left in a warehouse near peoples' homes, a ticking time bomb right in the heart of the city. In the days that followed, the human toll emerged. More than 218 people died, 7,000 were injured and 300,000 were left homeless.  More than two years after downtown Beirut was leveled by an explosion, a Lebanese-Canadian family is still searching for answers and accountability.