With Unicron seemingly defeated, Galvatron insists on settling things with Optimus, and the fight wakes Unicron again. Galvatron makes the ultimate sacrifice to finally end the threat. Jetfire and Hot Shot return the children to earth.
During the war on Cybertron, the Mini-Cons, mini-transformers who can be used as upgrades by their bigger brethren, crash lands on Earth. In present day, a group of children finds their ship by accident which brings the war to Earth.
The Decepticons gain access to the Autobot base, and attempt to take the other two minicons that, with the one Megatron captured on the island, combine to make the supremely powerful Star Sabre. Can Hot Shot save the day?
Enthusiastic young Sideswipe, Blurr's hero-worshipper, joins the team and Optimus tasks Hot Shot with training him. Wheeljack also arrives on earth, bent on revenge for Hot Shot seemingly abandoning him during a battle on Cybertron.
Desperate to make amends to his old friend, Hot Shot allows Wheeljack to shoot him, but this isn't enough. Wheeljack takes Sideswipe hostage, but Hot Shot rescues him. On the moon, Megatron welcomes Wheeljack to the Decepticons.
Hot Shot and Red Alert are sucked through a wormhole. The minicons guide the Axalon to their location, where they are all attacked by Nemesis Prime. As the planet breaks up, the 'Cons shoot down the Axalon and escape.
Escaping from the confrontation between Bots and Cons, Alex, Rad and Carlos find the cargo hold of the Exodus underground and are adopted by three minicons. Retreating to the moon, the 'Cons make the wreck of the Exodus there their base.
The Decepticons capture all the children to use as hostages in exchange for the Autobots's minicons. Fred and Billy are officially introduced to the Autobots.