Supposedly he's got a lawyer with $25,000 in a brown paper bag.

They follow the money.

What do you mean? Where?

Well, I can't tell you that.

But you could do.

No, I have to do this my way.

You tell me what you know, and I'll confirm.

I'll keep you in the right direction if I can.

But that's all.

Just follow the money.

Deep Throat, or Mark Felt, perhaps the most famous source of all time, portrayed there in a clip from the film All the President's Men.

That one source started off a chain reaction that would come to expose the Watergate scandal

and eventually bring about the demise of a president.

But while the tip of that monumental may be rare,

journalists' sources are an integral part of a huge number

of investigations. I know sources have been vital in some of my biggest stories, though I must

admit I can't say I've ever been summoned to a poorly lit parking garage to be fed tantalizing

snippets of information. But how do journalists meet their sources? How do two people,

moving along in parallel, one with a story to tell, the other trying to tell that story,

how do their paths converge? And what happens next.

I'm Maeve McClenigan, and this is The Tip Off, the podcast where we take you behind the scenes of some of the UK's best investigative journalism.

Our story today starts with this man.

...