The War Within issue 4

After falling down the deep chasm, Optimus Prime lies unconscious. When he's awakened by a magical, disembodied voice telling him about Cybertron, he wonders whatever happened to Megatron. Prime makes another attempt at looking within himself when Megatron arrives onto the scene. Megatron attacks, hoping to get the Autobot leader to surrender the Matrix of Leadership.

At the Tri-Torus Loop, Grimlock meets up with his running crew and begins to explain the plan to let the Decepticons conquer Iacon while the Autobot army scatters, taking out Decepticons who expect the Autobots to be too busy defending their capital. Meanwhile, Grimlock's crew use lines to go downwards, where Optimus Prime was last seen.

In Megatron's absence, Starscream takes his throne at Kaon and appoints himself Decepticon leader. The takeover doesn't sit right with Shockwave, but he is too busy leading the Decepticon army against several Guardian robots to challenge the change in leadership. Shockwave makes it clear, however, that they will discuss the situation—after he succeeds in leveling Iacon and winning a major military victory. Taking information from Laserbeak, Starscream verifies Megatron's belief about Cybertron having a deeper geography. However, Starscream plans to use this hidden aspect of Cybertron in a radically different manner than Megatron intended.

Megatron batters Optimus Prime, explaining how he needs the Matrix as a component in his "Make Cybertron into mobile dreadnought" plan. Prime isn't such a fan of the idea. The two battle, and Megatron gains the upper hand, cracking open Prime's chest to seize the Matrix.

The Matrix casts a blinding flash and when the light fades, Optimus Prime and Megatron find themselves somewhere different.

Featured characters

(Numbers indicate order of appearance.)

Autobots

Decepticons

Optimus Prime (1)
Grimlock (10)
Ironhide (11)
Kup (12)
Wheeljack (13)
Broadside (18)
Vibes (19)
Yellow and black Jumpstarter (see "Errors", 20)
Jazz (21)
Guardian robots (24)

Onslaught (16)
Fortress X (17)
Headstrong (22)
Ramjet (23)
Chop Shop (25)
Octane (26)
Blitzwing (27)
Blast Off (28)
Vortex (29)

Quotes

"This place seems to twist and turn of its own volition. But when in doubt... blow a big hole in something."

—Megatron

Notes

Optimus and Megatron's battle borrows a moment from the scene in The Transformers: The Movie when Hot Rod battles Galvatron.
On page 9, the street lamps are the same type as Soundwave's pre-Earth alternate mode in the first episode of the original cartoon.
The Decepticon killed by Broadside and co. is based on the Diaclone Fortress X toy.
Optimus has an Elita One bobble-head in his cab and an image of her on his mud-flaps in vehicle mode.

Errors

On pages 4 and 5, all Decepticons except for Starscream are miscolored: Motormaster is brown instead of gray; Runabout and Runamuck are two different shades of green instead of black and white; and Swindle is brown, with the center of his chest dark gray and the sides light gray, instead of orange with a purple chest. All these errors have been fixed for the trade paperback collection.
In the attack on Iacon a few pages later, Brawl, Quake, and Onslaught are severely miscolored as well. This was also fixed for the TPB.
On the same page, a massive, miscolored Broadside (with all the sections that are supposed to be red being blue instead; again, fixed for the TPB) stands next to a... female Autobot?
Also on the same page, Topspin's character model appears in Salt-Man Z's colors, yet the Salt-Man Z toy uses Twin Twist's mold. This apparent error was not corrected for the TPB, but given how riddled this issue is with coloring errors, it seems not impossible that it was an overlooked error. Thus, it is unclear if this individual is a new, separate character or just a miscolored Topspin.