The Maximals suffer their first casualty, and it's Justin. Wrongfully poisoned by Cyber-Venom, from Tarantulas, the poor boy's put in a coma. Feeling desperate and wanting to help, Aelita takes a risk and somehow transfers Justin's mind into a blank Protoform, becoming a new Maximal, K-9. While Aelita and the Maximals see as a way to help him, Megatron has found a way to manipulate the poor boy's fractured memories.
The Maximals gather around a stasis pod, which Justin discovers. Alex asks why the protoform can’t be activated, and Razorbeast grouchily replies that it’s a blank: a Protoform body without a spark. It was mainly used in case a body was too heavily damaged, in which Wind-Rider angrily states that they should never sacrifice the future for the past. So they decide to keep it in cold storage.
Before this can be done, the party is interrupted by an alarm. Predacons are attacking the new Air Force rocket base. The Maximals roll out to the base and engage the Predacons. During the battle, the rockets and their fuel are inadvertently destroyed, and Megatron orders a retreat.
To cover their escape, Megatron creates a diversion for the Maximals; he blasts at the roof, which topples atop Cheetor and Justin. The attack leaves Cheetor damaged and Justin comatose. Justin is taken to Antigo Hospital, where the doctors suggest that if Justin wouldn’t make it in time. Unless a miracle could happen, which Rachel begs to know what that is. The doctor, hoping to at least ease her, states that if there was such a method, Justin's mind could be transferred somewhere else, they would be able to operate on his fragile body.
Late that night, while labeling Justin’s condition terminal, the Maximals sneak Justin out of the hospital. With the help of Aelita’s power, Rhinox and Razorbeast transfer Justin's mind into the blank Protoform body. A beast mode of a German Shepherd has been scanned, and the transformation capability is successful. However, as a side effect of the transferral process, Justin's mind is in an extremely unstable state. Angry and confused about his new body, Justin, or K-9 as Rattrap joked, rampages, destroying several computers and machines in Razorbeast's med bay.
Optimus Primal is able to subdue K-9 without damaging his mind. To keep Justin calm, Rattrap and Rhinox tunes Sentinel to a television station, where cruel fate just happens to have scheduled an airing of a movie featuring Dr. Frankenstein’s unholy attempt to create life. Justin is roused to anger, convinced that he, like the Doctor’s creation, is a "monster." He again rampages throughout the Axalon, then escapes.
Alone in the wilderness, Justin suffers from the conflict between his own mind and what there is of the Protoform’s. Will he use his new body and powers to help the world like Optimus Primal, or conquer all Humanity?
Terrorsaur informs Megatron of Justin's new Maximal body and unstable mind, and Megatron forms a plan to trick him into destroying the Maximals. Megatron soon finds Justin, or K-9, with Spittor's help. K-9 attacks, but Megatron has other plans. Justin's unstable mind makes it hard for him to think, and he is easily twisted by Megatron to side with him against the Maximals.
Air-Razor brings the Maximals to Justin's location, but they are unable to fight against the vengeful being for fear of destroying Justin's mind. Only after Justin shoots his sister off the edge of a cliff does he realize what he has done. At once, he saves Rachel and turns on the Predacons.
Finally, Justin's mind is returned to his human body after the surgical operation is successfully completed. Afterwards, K-9's body is placed in stasis lock, hoping that one day, they'll know what to do with it.
"Oh, for bootin' up coal! Do we really need to go after him? Before he ran, he grabbed me by the face, and shook me like a ragdoll!"
"Oh, man! I should've been here to see that! That'd be so funny to see!"
Rattrap and Jackfoot arguing about Justin/K-9 being brought back.
Rattrap: "Yes, you did it again! Why do you keep grabbing my face? What is wrong with my face?!"
Jackfoot: "Would you like the list alphabetically or in descending order of grossness?"
- The idea for K-9 came from the Transformers G1 episode, Autobot Spike, in which Spike's mind is transferred into an Autobot Body made up of spare parts.
- This is also one of the tribute episodes for the G1 Transformers.