Wonderry Plus subscribers can binge full seasons of the Spy Who early and add free on Apple Podcasts or the Wondery app.

August 1949.

The Semi-Palatinsk test site, Kazakhstan, the Soviet Union.

A Soviet army truck thunders across an expanse of flat grasslands as it rushes

Igor Kurchatov towards ground zero. Khratoov is Russia's Oppenheimer, and he's just

detonated the Soviet Union's first atomic bomb. And in his eagerness to see the bomb site, he's

ignoring every radiation safety procedure he has put in place. The truck screeches to a halt next to the scorched soil and huge crater.

There is nothing left of the buildings that were around the bombside.

Geiger counter next to Kurchatov crackles loudly, warning of sky-high radiation levels.

Okay, enough. We can go.

Khrachatov leans back against the seat,

feeling the tension of the last four years begin to ebb.

After Germany's defeat,

Soviet leader Joseph Stalin finally gave him enough resources

to make a bomb based on the blueprints that Klaus Fuchs smuggled out of Los Alamos.

Yet even with the blueprints, so much could have gone wrong.

This successful Soviet bomb test means both he and his entire team

have escaped Stalin's wrath. Two weeks later, number 10, Downing Street. The head of Britain's

nuclear program, Michael Perrin, sweats in his suit as he faces Prime Minister Clement Attlee.

Prime Minister, we've detected a radioactive cloud that's drifting over the Atlantic.

The only possible explanation is that the Soviets have tested an atomic bomb.

Are you telling me the Soviets have already built and tested one?

...