Sinestro, former Green Lantern and foe of Hal Jordan, has begun the creation of his own lantern corps following his defeat in Green Lantern: Rebirth. After much time gathering ring-bearers who will "inspire fear" in their sectors, Sinestro and the Yellow Lanterns attack the Green Lantern Corps, killing many, freeing Superboy Prime, Cyborg Superman, and capturing Kyle Rayner, infecting him with Parallax. With their combined power, along with that of the newly resurrected Anti-Monitor, the Sinestro Corps seeks to destroy the Green Lantern Corps and conquer the universe.
The Guardians, in an attempt to even the odds in the ongoing struggle between the two corps, authorize the use of lethal force for Green Lanterns. With their full potential now realized, the Green Lantern Corps takes the fight to the Sinestro Corps, but it is revealed that the Sinestro Corps is attacking Earth. As Hal frees Kyle from the clutch of Parallax, Sodam Yat is appointed the new Ion. With the combined efforts of the Green Lanterns, Ion, and the heroes of Earth, the Sinestro Corps is defeated and Earth is saved once more. But the War of Light has begun...
Following his defeat in Green Lantern: Rebirth, the events of Green Lantern: Sinestro Corps Special #1 see the supervillain Sinestro retreat to the planet Qward in the Antimatter Universe. Here he amasses an army, the Sinestro Corps, that he selects based upon their ability to "inspire great fear". Each member is armed with a yellow power ring, mirroring the green ones of the Green Lantern Corps. Amongst Sinestro's allies are Parallax and the resurrected Anti-Monitor. The Sinestro Corps then launch an all-out assault against the Green Lantern Corps and the universe itself.
During the assault on Oa, the Sinestro Corps manages to inflict heavy casualties and free Superman-Prime and the Cyborg Superman from their imprisonment. Kyle Rayner is captured and transported to Qward, where Sinestro manages to separate Rayner from the symbiote Ion allowing Parallax to possess him.In Green Lantern (vol. 4) #21 the heroes Hal Jordan, John Stewart and Guy Gardner attempt to rescue fallen comrade Kyle Rayner, but are themselves entrapped, with Jordan transported to face Sinestro and his allies. A failed bid to rescue Jordan depicted in Green Lantern (vol. 4) #22 sees surviving members of the Green Lantern Corps forced underground and split into two groups. While one group attempts to free Jordan only to find themselves ambushed, the other successfully rescues Ion. They then re-unite with their ambushed comrades and together they escape from Qward back to the positive matter universe. Hal, John and Guy return to Earth to warn the Justice League of the Anti-Monitor’s return.
As the Sinestro Corps spreads out to ambush Green Lanterns across the universe, Green Lantern (vol. 4) #23 sees the Guardians decide to rewrite their sacred text, the Book of Oa. They remove a section devoted to a prophecy concerning the “Blackest Night”, against the objections of two of their number, Ganthet and Sayd. They then add 10 new laws, the first of which authorizes the use of lethal force against the Sinestro Corps, while Ganthet and Sayd are expelled from Oa. As the Green Lanterns gather on Oa in preparation for a Sinestro Corps assault, the Sinestro Corps teleport themselves and their Central Power Battery instead to a new Warworld, their objective revealed to be Earth. Events in Green Lantern Corps (vol. 2) #16 show Hal informing the Green Lantern Corps of Sinestro's plans.
Green Lantern (vol. 4) #24 continues the story, with Green Lanterns and Sinestro Corps members battling across Earth. Hal manages to free Kyle from Parallax before the entity is imprisoned in their power batteries by Ganthet and Sayd. After John and Guy arrive, the former Guardians reveal to them the prophecy of the “Blackest Night”, seen in Green Lantern (vol. 4) #25. It foretells of five more Corps arising, each based on a different color and emotion. After the five corps are established, a "War of Light" will ensue, in which all the corps are destroyed, leading to the “Blackest Night”.
The Guardians arrive on Earth and appoint Sodam Yat to be the new Ion. After a lengthy struggle in New York, the Sinestro Corps are defeated by the overwhelming numbers against them. One of the Guardians sacrifices himself to send Superman-Prime to an alternate universe, while Hal and Kyle subdue and arrest Sinestro in Coast City. In the aftermath of the battle, seen in Green Lantern (vol. 4) #25, the Guardians decide to bring the second of the new laws into affect. After realizing that the "Blackest Night" prophecy will come to pass, Ganthet and Sayd depart after creating a blue power ring with the intention of creating their own Corps, based on the spreading of Hope to the rest of the universe. The Anti-Monitor, having been blown across the vacuum of space at the battle's climax, finds itself on a dark planet. Here it is transformed by an unknown force into a Black Power Battery.