Following the extreme of the original, Mercenaries 2 pits you as a privately contracted 'militant' out for revenge against his previous client - who ended up betraying him and leaving him for dead. Nice.
Whereas the original Mercenaries was set in Korea, this time around you're in Venezuela as you track down the guys who set you up. Throwing the political commentary coin into the development fountain (where did that analogy come from?), oil is the big commodity in Venezuela with the country. Naturally, some bigwig is screwing with the oil, which leads to international crisis. Gotta fix that too if you want the cash monies.