They discover a fabled missing moon, which is under the control of Tyrest, famous for attempting to make two-state peacetalks between the Autobots and Decepticons early in the war, which failed but did result in the 'Tyrest Accords,' rules of war which both sides agreed to follow and enforced by Ultra Magnus.
Only Tyrest has gone loopy. He has Pharma (evil medicbot) working for him, and he's captured the Circle of Light (Drift's crew, the sword wielding bots). He's sponsored the decepticon titan hunters, and has created a line of personality-less bots called Legislatures to enforce his will with the tech obtained.
After the big trials (remember Last Stand of the Wreckers, the important data they were looking for? The information from these trials), he's decided that all Cold Constructed bots (bots made by spark-splicing rather than sparks found in naturally occurring fields on cybertron and it's moons) are destined to turn evil, and has enacted a plan to shut them *all* down (all Cold Constructed bots are made using the exact same copied code from the matrix, rather than having their own unique code, so if Tyrest can send a signal to stop that...). Every last one of them- Ravage, Prowl, Blaster...
Ultra Magnus is stripped of his position *and* his armor by Tyrest- it turns out that the original Magnus died way early in the war, and Tyrest created the 'Magnus armor' so that new bots could fill his shoes and be an 'immortal lawman'. The current one is a bot named Minimus Ambus, and is like the fifth Ultra Magnus (all the modern Magnus stories have been Ambus, btw).
Tyrest gives the position of Accord Enforcer to Star Saber, a religious fanatic traitor from the Circle (how he got past the Circle's defenses and captured them), and crushes Minimus's head.
Skids was really an autobot spy sent to make Tyrest retire with a piece of illegal tech (a 'thought gun,' which is also why he has amnesia), which is why those bots have been after him throughout the series, they're Tyrest's Legislators sent to tie up loose ends.
Tailgate has, like, three days to live due to a condition caused by sitting in a cave for several million years. Cyclonus is... not too happy about that. He decides to take out his anger on Tyrest's Legislator. Whirl, on the other hand, is happy, and he decides to take it out on Tyrest's Legislators.
And, well, pretty much everything goes down! It's big and epic and big.
A third book? I wonder if it'll be a mini/short series, three ongoings seem a bit much.
"And neither side knows what Shockwave is up to -- Soundwave (who's leading the Decepticons) considers Shockwave a traitor to the cause, and Bumblebee knows he's bad news, but neither know what he's up to. Will they side with each other against Shockwave, or will the Decepticons see Shockwave as a chance to reestablish their superiority?"
Because he was always looking out for his own interests. He worked with the Autobots because it helped him. He dealt with Swindle for cybertronian tech at the same time for the same reason. It caught up with him.
It's pretty good, imo. Completely different tone from Prime, even though it's technically a sequel. Much lighter in tone, almost Power Rangers with Transformers.
Of course Optimus is still Optimus. I don't think Peter Cullen could do light hearted if his life depended on it, so Prime plays the all business grandpa to the crews kids, ala Ben 10 dynamic, which actually works better then you'd think.