The raid on Germany's dams commences. The mission is off to a rocky start - two of the Lancaster bombers were forced to return home damaged, while a third was destroyed by enemy fire. As other crews make their way across Europe, more planes are lost and the first attempts to destroy the dams failed. But the tables are turned when 21-year-old pilot David Maltby and his crew release their bomb and breach the dam with devastating effect. Targets are destroyed, but at a shocking cost.