When Alexander Litvinenko set out for London's Millennium Hotel one November day in 2006, he already knew he was embroiled in a political conflict. The dissident Russian agent had, after all, fled Moscow to escape the wrath of Vladimir Putin and the country's feared security service. What he didn't realise was that the men he would drink with that afternoon were about to throw him into another battle: a brutal fight with a little-known but devastatingly toxic poison.
In an attempt to go green, governments around the world are shunning coal and embracing a supposedly better alternative: natural gas. It's a decision that will shape the future of our planet - but it may not be the right one. Meet Bob Ackley, former pawn shop worker and gas company contractor, who has spent years crisscrossing America collecting data on the gas leaks that pepper the country's cities. And what he has found could mean that the fuel may be as damaging to our climate as coal.