Not much is known about the origins or details behind this organization. Apparently, the Zodiac hoped that by surrounding New York City with a force field, it might turn the night black in order to sever the stars' influence on humanity and thus enable them to take over the city and, eventually, the world.
The Zodiac had created an army to help accomplish their mission, but the army was confronted by members of the Avengers. After gaining help from their erstwhile ally, the Enchantress, the Avengers followed the trail to the dimensional portal causing the force field, forcing their way through growing darkness and legions of Zodiac soldiers. The remaining Avengers managed to breech the force field to join their teammates in a final pitched battle against the Zodiac army and their costumed leader, Libra When the Zodiac's plans were thwarted, Libra escaped, but not before detonating small bombs in the Zodiac army's costumes and intimating that there may be other costumed leaders waiting to strike. To date, however, this version of the Zodiac has yet to reappear.