In 2014, a well-trained, mysterious band of mercenaries arrived in Ukraine, part of Russia's first attempt to claim the country as its own. Upon ceasefire, the ‘Wagner Group’ faded back into shadow, only to reemerge in the Middle East, where they'd go toe-to-toe with the U.S., and in Africa, where they'd earn praise for ‘tough measures’ against insurgencies yet spark outrage for looting,...