The documentary concludes with the story of the raid on Germany's dams, which got off to a rocky start as two of the Lancaster bombers were forced to return home damaged, while a third was destroyed by enemy fire. As the crews made their way across Europe, more planes were lost and the first attempts to destroy the dams failed. But then 21-year-old pilot David Maltby and his crew released their bomb and breached the dam with devastating effect. After this point, the targets were destroyed - but at a shocking cost.

The second episode focuses on the efforts of scientist Barnes Wallis as he attempts to get his revolutionary new precision weapon, the bouncing bomb, to work. After several attempts, a functioning bomb is tested and a full dress rehearsal is carried out. Gibson, now confident that his men are ready, prepares 617 squadron for their high-risk mission.

The first episode focuses on the recruitment and training of the airmen for the mission, with Commander Guy Gibson given just eight weeks to put together a crew able to fly at low altitudes at night, as well as the development of the bouncing bomb.