The Decepticons have been provided with a suitable fuel by the human Sparky Witnicky.
As the Decepticons make their preparations for a final attack on the Autobots, the Autobots argue amongst themselves as to the actions of Sparky and the role of humans in general. During the argument, Sparky suffers a heart attack and is taken to the local hospital by the Autobot Ratchet.
Finally, the Decepticons attack leading to a massive battle. When the Decepticons have essentially beaten the Autobots, the Decepticons all collapse due to a hidden acid Sparky put in the fuel he created for them. However, as the Autobots, fatigued from the battle, celebrate the apparent victory over the Decepticons, the Decepticon Shockwave appears to finish off the weakened Autobots.