Professor Robert Paaswell, and two of his students Rachel Becker and Marty Cooper are exploring the Oregon wilderness when they find giant tracks that are possibly that of dinosaurs. They are in fact the Dinobots, who have been roaming the area since they defected from the Autobots. They spot Swoop flying by and decide to investigate further. The Dinobots meanwhile help themselves to an oil tanker for their next meal, and Grimlock orders his troops to head back to the Ark after getting a spy report from Swoop informing him of Optimus Prime's death, Grimlock intends to take over leadership of the Autobots.

Meanwhile, on the Florida Island that is now the headquarters of the Decepticons, Shockwave gets into contact with Ratbat, the fuel auditor on Cybertron. Ratbat informs him that they must shut down the Space Bridge as it is too costly to collect energy through it and they intend on discontinuing its use. Shockwave manages to appeal Ratbat to at least let them use it once more to send over the most deadliest Decepticon on Cybertron to launch a surprise attack on the Ark.

At Autobot headquarters, Jetfire, Perceptor, Blaster, Hotspot, Ratchet Omega Supreme and Silverbolt all meet to discuss who is to lead the Autobots following the passing of Optimus Prime. Grimlock crashes the meeting telling them their leader needs to be strong and merciless like him. When the other Autobots refuse to accept Grimlock as their leader the Dinobot commander storms off vowing to show them that he will take over the Autobots by any means possible.

That night, Rachel Becker is awoken by a strange light and witnesses the Space Bridge materialize in the forest where it delivers its deadly cargo, the Decepticon known as Trypticon. The gigantic Transformer transforms into city mode and lets loose his sidekick Wipe-Out and then begins bombarding the Ark with sonic missiles, drawing out the Autobots. The Autobots get trounced by Trypticon's superior firepower. The commotion draws Rachel and the Dinobots to the location. The Dinobots decide to sit back and gloat at the Autobots are beaten mercilessly. When Grimlock spots Rachel and she doesn't run away from him he is impressed by her bravery and leaves her, leaving her open to being captured by Wipe-Out.

Wipe-Out brings the girl to Trypticon who is interested in toying with the girl, this prompts Grimlock and the other Dinobots to attack Tyrpticon. The Dinobots are more than a match for the giant Decepticon and eventually, Ratbat returns the Space Bridge and orders Trypticon to return to base as he has expended too much energy, ending the battle. With the battle over, the Dinobots return to the Ark, leaving Rachel to be found by her friends and explain what happened.

Inside the Ark, the other Autobots are convinced that Grimlock has proven himself a capable leader and name him the new commander of the Earthbound Autobots.

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