This is The Guardian.

It's 2014 and a new venture in Scotland is starting to generate a buzz.

When I first came here, I met the fellow community, the agricultural community,

and they asked me what I was going to do here.

And I told them I was going to grow tea.

And there was a sort of raising of eyebrows and a few rise smiles, and they just went, hey, right.

Explaining his audacious entry into the world of tea growing to BBC presenter Mark Stephen is Tam O'Brien.

My name's O'Brien and as you can see the river that marks out the boundary of our land

is the brand, the river brand, which the whole of the glens

named after. So they've renamed to me. I'm no longer Tom O'Brien. I'm Tam O'Brien.

Back then, I wasn't long into my career as a science journalist.

And it would be a few months until I met Tam myself for a feature I was writing.

And in the decades since, there's been a question tucked away at the back of my mind.

Something that I just couldn't figure out.

Until now.

And over the next three episodes, that's the story you're going to be hearing.

I'm Nicola Davis, science correspondent at The Guardian.

This is a special mini-series from Science Weekly, a Scottish tea mystery. Episode 1, Green shoots

Let there be no doubt, journalists love a quirky story.

And for a British journalist like me, what's better than a quirky story about tea?

Which is why, in 2015, I ended up in one of London's fanciest hotels, The Dorchester.

By the time we met, Tam O'Brien, had already been making waves with his new venture.

...