Earth One Green Lantern Vol2.
Three years following the events of volume 1
... Earth has begun talks with alien worlds. Their first visit however doesn't go well, as one of the alien ships exploded in Earth orbit, causing them to retaliate against a military space station. Hal begins to investigate, but gets sidetracked when the GL Corps detects the Manhunters returning to Oa. The GLs take the opportunity to attack in order to reclaim the planet, but find the Manhunters already taken out, thanks to a Guardian and his new Yellow Lanterns. He wants the GLs to join his new Corps, but Hal doesn't trust him, given his plan in the previous volume involved sacrificing the slaves the Manhunters had taken. Many Green Lanterns (such as Sinestro and Tomar-Re) end up taking the Guardian up on his offer.
Finding out a Yellow Lantern was responsible for the destruction of the alien ship at Earth, Hal figures out the Guardian actually arranged the whole situation, and was in league with corrupt elements within Earths government. Before Hal is able to do anything about it though, the Guardian has the Yellow Lanterns attack the remaining GLs, and takes out the GL Central Battery which instantly depowers them. Hal, being in space at the time, is saved by the ambassadors of Earth who'd been taken hostage following the incident at Earth (and subsequently freed by a Qwardian that gave them his Yellow power ring because he disagreed with what the Guardian was doing), as well as a human built prototype FTL ship.
Believing the Guardian transported the GL Central Battery to another universe the Guardian had escaped to during the Manhunter invasion, Hal and his fellow humans launch an attack against the Guardian's ship. Hal confronts the Guardian alone, whom offers Hal the chance to join him once again, revealing his evil plot to remake the universe as he sees fit, which Hal obviously turns down. The attack.. doesn't go according to plan, but they get some backup from a few GLs that managed to survive and arrive in either ships or with Yellow Rings, as well at the rest of the Yellow Lanterns that turn against the Guardian. Hal manages to kill the Guardian and destroy his ship, but ends up trapped in a parallel universe, where the Green Central Battery turns out had been transported to, and becomes the new "Guardian" (a name he wishes they wouldn't call him) to the Qwardian people.
Honestly, I did not enjoy this volume as much as the first. The plot just seems a little... all over the place, and too convenient at times. Like with the Manhunters... The Guardian does explain the Yellow Lanterns are more powerful than the Green Lanterns (and Green as it turns out is more powerful in the parallel universe), but they are taken out way too easily. There's also really nothing to establish how the Yellow Lanterns are any different from the Green Lanterns here, beyond being somewhat more powerful. The Green Lanterns speculate that the Guardian might hold some sort of control over them, but when Sinestro questions him at one point, there's no indication the Guardian has any influence over him, and simply tells him to follow his orders so long as he wears a Yellow ring. I also would have liked a little more follow up at the end... I suppose it is left open for another potential sequel though. John Stewart is featured in this book as one of the Earth ambassadors (for some reason, it seems odd an architect/former soldier would be chosen as one of three people to be the first ambassadors to an alien race). He ends up with a Yellow ring, but he's not sure if he will keep it or not at the end of the story. And given the Yellow Battery is in one universe, and Green is trapped with Hal in another, does that mean the Yellow Lanterns will replace the Green Lanterns as the police force in the universe? That's the impression I get is that is where they're going, but it isn't really established.