The Parallax story is the perspective of Kyle trapped inside he's own body watching Parallax hurting he's friends and killing he's fellow Lanterns, while being tormented by Parallax over he lost loves and the death of he's mother and striving to fight Parallax to try regain control of he's body. Cyborg Superman's story shows him on he's way to Earth on board Warworld talking to Sinestro and readying he's Manhunters but he's mind is on he's origin that gave him he's powers, becoming the Cyborg Superman, and he's previous battles with Superman, then starting he's attack on the Justice League and getting the upper hand on Superman. Superboy-Prime's story start's with him defiling Bart Allen's memorial statue as the combined force of the Justice League and the Justice Society teleport in to try and take him down before he's fully recharged by Earth's yellow sun, though is only truly challenged by fellow Kryptonians Superman, Supergirl, and Powergirl but even fighting them off he still makes it to sunrise in New York and grows even more powerful and sees a new challenge in the newly appointed Ion.
The last one-shot story starts Hal, Guy, and John at a campfire waiting for Kyle whose talking with the Guardians of The Universe about their recent decisions and actions, after Kyle gets he's answers they ask him if he could talk to the new Ion, Sodam Yat, and give him some advice as former host to Ion, and help him over come he's defeat at the hand's of Superboy-Prime. Kyle meets with Sodam and they talk in space above Oa but suddenly come under attack by Alex Nero, who want revenge against Kyle and The Guardians of The Universe, Kyle and Alex are evenly matched, but Sodam uses he's new Ion powers to take control of Alex's constructs which momentarily connects Nero to the Ion entity and overloads he's mind allowing him and Kyle to take him in. Kyle then meets up with he's fellow human lanterns campfire on an asteroid , and tell them what took him so long, and he's new assignment as an Honor Guard as Guy Gardner's partner.
Then there's one last short story about Morro, the Crypt Keep of Oa, of how he got he's pet dragons that are always with him. The rest of the book are the secret files of the Green Lantern Corps, and the Sinestro Corps, which are just pics and short bios of all the various GLs, SCs, and other equipment and entities, that have appeared in GL stories so far. Like I said the great part of this book is the one-shot stories that gives better insights and more action to the villains, especially the Super-Boy which I felt should been in the main story cause it lead directly in to he's fight with Sodam Yat and explains why he's not in he's full armor at that time.
So if you loved the Sinestro Corps War, and want more stories with them, or just want to see more action with Superboy-Prime and Cyborg Suserman, then you'll need this, a great companion book to the two Sinestro Corps War volumes.