Our universe is a dangerous place, and our peace is fragile. Dark lord's are trying to claim the many worlds we occupy, create giant massacres, holocausts, start galactic wars, you mention it.
In the year of 2825 the world leaders decided to try and end this evil, by making organizations of selected powerful women as guardians of this peace. Throughout time they will preserve our peace, through many generations, as their leaders will live longer than the common rabble, due to having their DNA manipulated to a longer lifespan.
This is the story of one group, the Sirens. They weren't the most wanted and acknowledged in the beginning, since their leader was formerly a criminal, but they soon enough proved to become the most valued group of them all.