On December 6, 1917, the French cargo ship Mont-Blanc, loaded with wartime explosives, collided with the Norwegian vessel Imo in Halifax Harbour. The resulting blast leveled the Richmond district of Halifax, killed roughly 1,500 people instantly, injured about 9,000 more, and flattened everything within a half-mile radius, remaining the largest human-made explosion before the atomic bomb. This Spark production combines archival photographs, period accounts, and expert interviews to reconstruct the chain of errors that put two ships on a collision course in a crowded wartime harbor, and the chaos that followed as fires spread through wooden houses and a blizzard hampered rescue efforts the next day. The film traces the immediate aftermath, including the makeshift hospitals set up in surviving buildings and the international relief effort, particularly from Boston, that arrived within days. It also examines how the disaster shaped later thinking about industrial accidents and emergency response, using survivor testimony and harbor maps to walk through exactly how a routine shipping error became a catastrophe.