Rise of the Helghast

In R2 Turn 19 Lelouch found himself dying with Kallen in his arms. But a group of people with unbelievable power have come to help him in his hour of need. Who are these men in gas mask's. Where do they come from. There is something that has been hidden from the rest of the world and now it is time for it to be reviled. DOWN WITH BRITANNIA LONG LIVE THE HELGHAST!