No one really knew when it started.
No one really knew who the invaders were, or where they came from.
All anyone knew is that quietly one day in a random part of the world it started.
Starting with only a few individual people at first, and then entire towns. One at a time fell to the invaders. However, unlike what humanity saw in numerous science fiction movies the invaders were not killing people. They were transforming them. Like a plague the invaders were turning everyone into new members of their forces. Day by day their numbers grew while humanities dwindled.
Anyone they transformed seemed to achieve perfect health forever free from disease, and injuries. They also gained greater strength, reflexes, and stamina. Adults seemed to stop aging somewhere in their mid twenties. Anyone older than that grew younger until they reached that age. Children that where transformed continued to age normally until they reached their twenties than stop. They also gained the same benefits as the adults.
Those transformed became fully functioning members of the invaders forces. Apparently willing to join, and help them take the rest of the planet. Nothing seemed able to break thru this mental transformation so far.
The worlds united militarizes, and governments under the command of the United Nations wanted to keep the last a closely guarded secret in case there were those that might willingly let themselves be transformed for whatever reason. Unfortunately, like all attempts to bury a secret it eventually leaked out by word of mouth.
So far nothing the United Nations did seemed able to stem their advance. Conventional military attacks so far had proved useless, and before they began the invaders had somehow deactivated the entire worlds stockpiles of nuclear weapons.
It seemed that nothing could stop them from eventually taking the world, and the human race.
Unless a way could be found to stop them the entire human race would be transformed into.....