Starscream, Thundercracker, and Skywarp raid a munitions plant to collect its energy and send it to Cybertron. Meanwhile, Optimus Prime and Spike Witwicky are on assignment to locate the next place the space bridge will appear. Chip Chase, who happens to be at the plant, contacts Optimus Prime and asks for help. Optimus and Spike go in alone with reinforcements on the way, but their friends arrive too late. The Decepticon trio gravely damages the Autobot leader, already weakened after shielding Chip and the munitions plant director from an explosion, and his condition is so critical that a special component must be replaced if he is to survive. The problem is that a replacement can only be found in Wheeljack's old workshop on Cybertron. As the Autobots ponder the predicament, Laserbeak appears and blasts Optimus Prime's chest in an effort to kill him. Optimus miraculously manages to survive the assault. Ironhide, Trailbreaker, Bluestreak, Bumblebee, and Chip, determined to save Optimus at any cost, then attack the current space bridge location. Megatron orders his subordinates to let the Autobots make the journey to Cybertron unhindered, where other Decepticons will dispose of them. Shortly after their arrival, the Autobots locate the replacement part, but before they can get back to Earth, Decepticon jets impede them by creating acid rain, capable of completely disabling Transformer circuitry. When all seems lost, Chip inspires his friends not to give up and the group manages to make their way back from whence they came. On Earth, the Decepticons launch what they believe will be the battle to end all battles, but just as defeat seems inevitable, the repaired Optimus Prime takes advantage of the energy-depleted condition of his enemies and wins the day.