Hi, I'm Rosa Ellis, presenter of the BOM season 2 from the BBC World Service.

It's a gripping espionage thriller about Klaus Fuchs, the man who's been described as the world's

most dangerous spy. To leak atomic secrets to the Soviets, he needed the help of their prized

spymaster. And this is where the story gets personal. That star-soviet spymaster is part of my

family history. She was my great aunt. As a special bonus for listeners of the documentary,

I thought you might like to hear episode one. You'll only get this episode here. For the rest,

search for the BOM wherever you found this podcast.

It's 3am on Monday the 10th of September 1949. In the North London home of Michael Perrin,

director of Britain's Atomic Energy Program, the telephone rings. Perrin is startled from his dreams.

Still half asleep, he rolls out of bed and grabs the phone. A voice on the line delivers an urgent

message. The Americans, what could they want? His mind races. He finds no answers, but he knows it

must be serious. He rushes to get dressed and hurries out of the door into the dark night.

He jumped in a taxi, made a 15-minute ride down to the middle of London, went to the embassy where he

was hustled into the secure communications room there by the US State Department officials.

There were several coded telek's messages that had come that evening from the Pentagon

that said the US Air Force, using especially equipped planes, had detected radiation in the atmosphere.

There can only really be one explanation. Four years after atomic bombs have devastated the Japanese

cities, Hiroshima and Nagasaki, the Soviets have exploded an atomic bomb of their own.

British and American scientists have assured their governments that Russia is three or more years

away from getting the bomb. But this news completely reshapes the post-war landscape. A Russian bomb

challenges American global supremacy. And for the Brits, it could mean obliteration. Moscow is only

1,500 miles from London. How can this have happened?

...