We rarely stop to consider where they have come from. But we should.

In The World for Sale, two leading journalists lift the lid on one of the least scrutinised corners of the world economy: the workings of the billionaire commodity traders who buy, hoard and sell the earth's resources.

It is the story of how a handful of swashbuckling businessmen became indispensable cogs in global markets: enabling an enormous expansion in international trade, and connecting resource-rich countries - no matter how corrupt or war-torn - with the world's financial centres.

And it is the story of how some traders acquired untold political power, right under the noses of western regulators and politicians - helping Saddam Hussein to sell his oil, fuelling the Libyan rebel army during the Arab Spring, and funnelling cash to Vladimir Putin's Kremlin in spite of western sanctions.

The result is an eye-opening tour through the wildest frontiers of the global economy, as well as a revelatory guide to how capitalism really works.