It was a night that changed the Second World War. The secret air raid against the hydroelectric dams of German's Ruhr River took years to plan, involved an untried bomb and included the best aircrews the RAF Bomber Command could muster, many of them Canadian. The raid marked the first time the Allies successfully took the war inside Nazi Germany. It was a mission that became legendary. On May 16, 1943, nineteen Lancaster bombers filled with 133 airmen took off on a night mission code-named Operation Chastise. Hand-picked and specially trained, the Lancaster crews flew at treetop level to the industrial heartland of the Third Reich and their targets the Ruhr River dams, whose massive water reservoirs powered Nazi Germany's military industrial complex. Each Lancaster carried an explosive that, when released just sixty feet over the reservoirs, bounced like a skipping stone to the dam, sank and exploded. The raiders breached two dams and severely damaged a third. The resulting torrent devastated power plants, factories and infrastructure a hundred miles downstream. Every one of the 133 airmen on the mission understood that the odds of survival were low. Of the nineteen bombers outbound, eight did not return. Operation Chastise cost the lives of fifty-three airmen, including fourteen Canadians. Of the sixteen RCAF men who survived, seven received military decorations. Based on personal accounts, flight logs, maps and photographs of the Canadians involved, Dam Busters recounts the dramatic story of these young Commonwealth bomber crews that were tasked with a high-risk mission against an enemy prepared to defend the Fatherland to the death.