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Fritz Vierman steps out to the brick factory. 1974, Amsterdam, the Netherlands.

Fritz Viemann steps out to the brick factory building he works in and into the drizzling rain.

He unfurls his umbrella and hurries towards the nearby bridge over the canal.

He looks back to check no one's following him.

Then he checks again.

Veerman works for a company called FDO.

It designs components for ultra-centrifuges that enrich uranium.

These advanced centrifuges are mainly used for nuclear power,

but they can also produce uranium for nuclear weapons. And that's why FDO's designs are classified.

The airman reaches a street with a smattering of shops and approaches a phone booth.

He checks he's not being tailed once more, then steps inside.

He calls a number he's jotted down on a scrap of paper.

A secretary answers.

Director's office, Jureenko.

Yerenko is FTO's biggest customer, a nuclear technology consortium founded by the British, German and Dutch governments.

I need to speak to the director.

He's busy right now.

I must speak with him.

It's very important.

Well, he's unavailable.

...