Season 3 Episode 13 – Endgame, Part II
In the Season 3 finale, the Autobots battle against the Decepticons in the ultimate showdown.
Five Autobots (Optimus Prime, Bumblebee, Ratchet, Prowl, and Bulkhead) find the fabled Allspark only to become a part of the long-lasting battle between the Autobots and their enemies, the evil Decepticons. A space battle ends up stranding the Autobots in the 22nd century Detroit where they take on roles akin to that of superheroes, fighting both Decepticons and human supervillains. The story takes place in Detroit, and the Transfomers' battle is renewed in this future city on Earth. Instead of being known as the Motor City, it has now become the Robot City due to Dr. Isaac Sumdac's non-alien robotic creations. Sari Sumdac, his 8-year-old daughter, is the main human character that the Autobots saved when they landed on Earth.
In the Season 3 finale, the Autobots battle against the Decepticons in the ultimate showdown.
The Autobots discover Arcee's energy signal on the Moon. Rachet insists on going there right away to save her, but Prime refuses, knowing that they are too weak to fight Megatron. Rachet, Sari and Professor Sumdac build flight boosters for Optimus to even the chances. Prowl tries to put the Allspark back together, using processor over matter. Meanwhile, Shockwave finally gets Arcee's codes and uses it on protoforms (stolen by Starscream, to make his clones) to duplicate Omega Supreme. Finally, Omega Supreme's clones fly from the Moon to invade the Earth. The episode also shows some of Optimus Prime's memories about being expelled from Elite Guard and meeting the other main characters.
Ratchet activates Bulkhead's Space Bridge, which ends up sucking Captain Fanzone into it with Ratchet following him. They both end up on Cybertron around the time Sentinel Prime has declared a lockdown. Omega Supreme has arrived on Cybertron with Megatron, Starscream's Head, and Lugnut; thus, Shockwave, still posessing Ultra Magnus' hammer, attempts to get Omega's access codes from Arcee herself.
The Space Bridge on Earth is finished. Meanwhile, the Elite Guard ship holding most of the Decepticon prisoners heads straight into an ominous space storm. The space storm reactivate Swindle who frees the Decepticon prisoners and takes over the ship. Optimus Prime identifies the "Broken Lance" code from Sentinel Prime and uses the Space Bridge to transwarp to the ship. The title may be a reference to the movie Con Air which has a similar plot.
It turns out that Soundwave has trapped the Autobots in a virtual reality intending to brainwashing them to his way of thinking. Now, Sari must free them before Soundwave completely turns them into Decepticons. She leads a ragtag team of allies - Snarl, Scrapper, and Wreck-Gar - into battle against the Autobots.