A woman types an anonymous letter. She’ll never know - but it will trigger a battle from red brick England, to the skyscrapers of Manhattan.

In this series, casually scanning old newspaper archives, Ophelia Byrne comes across an odd headline: “Hush hush process in Ballyclare firm.”

The newspaper was printed in 1967. “Strictly no photographs” was the order issued at the opening of the new factory.

All workers “will have to sign an oath of secrecy.”

What, she wonders, is this factory making?

Ophelia doesn’t know it when she starts out, but her subsequent investigation into this company, Turner and Newall, will take her from a small town in Northern Ireland across the Irish Sea to places like Rochdale, Leeds and London.

It will bring her to one million documents released for a transatlantic trial – papers which show cover-ups and even corporate espionage.

The product, of course, is asbestos. You may think you know the story – it’s a dangerous substance.

But Ophelia marries previous journalistic investigations to new documents which reveal what government agencies knew about its risks, and when.

She combs through company correspondence which the manufacturers claimed did not exist, and clearly never imagined would become public.

It is the story too of the people who fought and died for the truth to expose the reckless pursuit of profit in the making of one of the most dangerous building materials on the planet.

Presenter/ Producer: Ophelia Byrne