It's entirely up to you.

EDIT: Let's not reveal the whole "Cure the virus to enter a secret society" part. I want that to be the surprise at the end. Only the higher-ups know about it. Instead, how about "Elysium is trying to gain control of the world, so they're going to kill (or threaten to kill) everyone with a virus. We keep improving it until it cannot be cured. It's currently at (whichever stage of advancement the virus is at, maybe only the second or third). Even if you cure the virus, you'll be killed." The reality can be withheld until the end. 

Assuming we cure the virus, we can say that as soon as we cure it we are captured, but rather than killing us they reveal the truth and we are...sent somewhere. I dunno. Maybe we just join them?