In 1957, Britain exploded its first megaton hydrogen bomb - codenamed Operation Grapple X. It was the culmination of an extraordinary scientific project, which against almost insuperable odds turned Britain into a nuclear superpower. This is the inside story of how Britain got 'the bomb'.

Following the events from the death of US President Roosevelt through to the dropping of the two bombs on Hiroshima and Nagasaki that prompted Japan's surrender.