You are dead.
When you were alive, you were a soldier. You fought well and valiantly for your life, for your country, for the survival of your very species in a war against an enemy from beyond the stars. But in the end, when you died, there was nothing left of the body. An empty casket was buried. You had gone to a better place. That was what the government wanted your loved ones to believe.
It was a lie.
A secret government organization known only as EXTRA has taken what's left of your remains... And they've grown you a new body. One that looks exactly like the monsters you died fighting. They want you to infiltrate their ranks, to gather as much information about the enemy as possible. But the body in which you've been resurrected has a mind of it's own, instincts that must be controlled.
At least they aren't sending you in alone.
This is VERY loosely based on a story I read once on DeviantArt... I understand the concept's a little bit vague, but I certainly feel like it has potential. I'll try to go deeper into it where I possibly can if I ever get to the OoC/IC phase, or even right here if I think of more details.