JO OK. I've written down the thing which, if it became known, would destroy my political career. And I'm going to give it to Sam. As long as he does the same and gives his to Peter, and Peter does the same and gives his to me. And we know that if we reveal the thing that we've been given, then the person who's revealed it will reveal our thing. SAM How do you know there'll be a thing? JO Because there always is. It's 16 April 2010, the day after the first prime ministerial debate. Stranded in Malaga Airport by the Icelandic ash-cloud, a Labour special advisor, a Lib Dem staffer and a Tory candidate consider their options. Can their parties survive without them? How will they get back home? And who'll end up in government? And now it's 4 August 2014. As the nation settles down to commemorate the outbreak of the First World War, the three politicians meet again. One of them knows something that could change the outcome of the 2015 election. Should they reveal it? And at what cost?