Can someone please explain the "Panama Paper"scandal briefly?

The top 1% wants to minimize taxes on income and wealth transfers and so for decades have hidden money offshore (not in their home country). This is particularly important in the U.S. because it is one of the few, if not only, countries that tax foreign income. So various offshore, hidden tax entities were set up in various countries such as the Cayman Islands where less disclosure in required. The Panama Papers was the release of a lot of data about these activities and the individuals involved.