Killzone: Mercenary is set after the events of the first Killzone and revisits many of the events from the Killzone trilogy. It runs on the Killzone 3 engine. It puts players in the boots of mercenary and former UCA-soldier Arran Danner, commissioned to do work for both the ISA and Helghast. He doesn’t pick sides, so long as he’s paid. But after a mission to evacuate the Vektan Ambassador and his family in Pyrrhus goes wrong, Danner realizes the war’s outcome is dependent on the fate of the Ambassador’s young son, who both the ISA and Helghast are trying to seize.