One of the most famous and spectacular events of the Second World War was the destruction of two dams in the Ruhr by Avro Lancaster bombers of 617 Squadron, known ever since as the Dambusters Raid. The bombs that the Lancasters dropped were designed by the most prolific inventor of armaments of the period. His Tallboy and Grand Slam earthquake bombs helped destroy the battleship Tirpitz as well as numerous other high-profile targets, and were only eclipsed in destructive power by the atom bombs dropped on Japan. The inventor was Barnes Wallis and A Hell of a Bomb is the story of the development of his bombs, their destructive uses and how they helped win the war for the Allies.