The Fallen, one of five enemy races in Destiny, have breached the Wall that surrounds the City, the last safe city on Earth. They have acquired the SIVA virus, a Golden Age breakthrough in self assembling nano technology, giving them an arsenal of new weapons and tech not previously seen. Lord Saladin, the last remaining Iron Lord, will lead players as they discover the past of the Iron Lords, reclaim Felwinter's Peak, and stop the evil that the Iron Lords had originally sealed away. Players will set out to become the new generation of the Iron Lords.
Source: Wikipedia, "[en.wikipedia.org/wiki/Destiny%3A_Rise_of_Iron Destiny: Rise of Iron]", available under the CC-BY-SA License.