The Panama Papers is by sheer volume of documents the largest whistle-blower leak in history. With over 100 news organizations from over 80 countries involved it is also the largest journalistic collaboration ever. And it has already claimed its first scalp.

On Tuesday, Iceland Prime Minister Sigmundur Gunnlaugsson resigned over revelations of undisclosed investments in three of Iceland’s failed banks.

But the 11.5 million documents from the Panama law-firm Mossack Fonseca also expose shadowy dealings surrounding dictators and kleptocrats worldwide — with 99% of the iceberg still submerged.

The material has been scrutinized by some 400 reporters for the past year, under the coordination of the International Consortium of Investigative Journalists. Bob speaks with the consortium’s director, Gerard Ryle, about how the global investigation came together.