4. The Visit, Part 1

Subscribe to follow BBC News anchor Ros Atkins' funny, fascinating and sometimes awkward friendship with one of America's most notorious broadcasters.

Two years after the texts first started and despite never having met, BBC News anchor Ros was now exchanging more texts with legendary US broadcaster Keith Olbermann than anyone else apart from his wife. They often arrive as he's making the late night trip home after his show - and they continue when he's catching up with his wife in bed. It's time to ask Keith 'why?' and to ask his wife what she makes of it.

Keith is both famous and infamous in part because of his political polemics and very public fall-outs. And that comes at a cost: he regularly receives death threats. Ros never has. And he wants to know: Does Keith ever regret the constant conflict?

Keith Olbermann is one of the very few journalists in history who've become multi-millionaires. Ros isn't. They explore where money fits into their definitions of success - and Keith reveals a story from 2008 involving the Republicans, MSNBC and an awful lot of money. He also has to explain why he sponsored the match ball at the tiny football club at the end of Ros' road in London - without Ros ever having mentioned it.

After two and a half years, the time has come. The BBC sends Ros to New York for work and, after talking to super-connected media executive Vivian Schiller, he heads to Keith's penthouse overlooking Central Park to meet the man behind the texts.

Ros gets a crash-course in American cable news as Keith grudgingly flips through the channels while they sit on his sofa.

Are Ros and Keith tiptoeing into a real friendship? As usual it's Ros' wife who sees through to the heart of the matter.