Captain Marcus Chaplin
Marcus Chaplin is the Captain of the USS Colorado, which is the Ohio-class submarine. When he receives an order to fire a nuclear strike on Pakistan, he questions it, instead of following it. This makes him, and his senior officers guilty of mutiny and treason.
Marcus has always been a man of honor, but after this event, he takes a new course; which could either be great and noble, or devastating in the end.