Ratchet thinks back on the time that he spent in the Autobot-Decepticon War. Meanwhile, he must face his past when an old Decepticon foe appears, the bounty hunter Lockdown. The episode opens with Ratchet, Optimus an Bumblebee at a car shop, with Ratchet remarking that it's ridiculous that they just "sell" spare parts. However, Optimus and Bumblebee try to convince him to enjoy the present more, just when the lights black out. They are then nearly run over by a muscle car. Optimus orders the Autobots to take it down.
The muscle car starts heading for a couple of civilians, and Optimus barely saves them by making a makeshift ramp with a billboard, sending the car into the air. It starts flying toward Ratchet, and he enters a flashback sequence.
Back in the Great War, Ratchet is in the middle of a battle on Cybertron. He is radioed by Ultra Magnus, who orders him to locate an intelligence officer with important information. He then locates Arcee, who has the codes stored in her memory core. Ratchet uses a mild EMP to make her lose consciousness so he can repair her damaged leg, and then he hears a loud noise before falling back into the present, nearly being trampled by the muscle car as it crashes into the ground and drives off.
Back at the Autobot base, Ratchet is performing self tests, and Optimus tries to talk to him, but Ratchet shrugs him off. Prowl then shows the other Autobots a news announcement about the muscle car as it drives through Detroit, apparently causing blackouts in buildings it passes by. Listening to this, Ratchet falls back into the flashback.
Ratchet quickly repairs Arcee's leg and transforms into ambulance mode, loading up Arcee into the back. As he's driving through some tunnels, the same muscle car starts chasing him. Ratchet tries to race off, but he stumbles into some spikes on the ground and his tires blow out. He unloads Arcee and transforms to face the muscle car, who in turn transforms into the Decepticon bounty hunter Lockdown. Ratchet and Lockdown have a brief fight before Lockdown knocks Ratchet out.
Bulkhead brings Ratchet back, saying that the Autobots are going after Lockdown. The Autobots roll out, and start chasing Lockdown on a highway. Lockdown fires a beam of light that blinds the Autobots and he disappears. Ratchet then realizes who he is before falling back into the flashback.
Ratchet and Arcee are both tied up in Lockdown's hideout. Ratchet tries to use his magnet beams to remove his binds, but they're made of a non-metallic material. Lockdown then introduces himself as a bounty hunter who works for the Decepticons because they pay good money. He also states that he enjoys the hunt because it gives him trophies, such as Ratchet's EMP detonator.
Ratchet is pulled back into the present, with Optimus chasing Lockdown. Lockdown transforms in front of Optimus and blasts him with his EMP launcher, knocking him out. He then fires a smokescreen that covers his escape before the Autobots can save Optimus.
The Autobots try to locate Optimus' energy signal, but can't find anything. Ratchet then tells the Autobots about Lockdown, including the fact that it was him who gave him the chip on one of his horns. The scene switches to Lockdown's hideout, where he has Optimus tied up. Lockdown explains that there's a bounty of Optimus' head because as far as everyone knows, he's the one who "killed" Megatron. Optimus nearly escapes using his grapple cannons and his energy axe, but Lockdown knocks him out with another EMP. He then proceeds to slice out Optimus' grapple cannons with a chainsaw.
Using satellite imagery, the Autobots discover that Lockdown is using a hologram to mask his ship. Lockdown is then shown conversing with Blitzwing on a video feed, with them talking about Optimus' bounty. Just then the Autobots arrive outside the warehouse, and laser beams try to take them out. Prowl manages to leap ontop of the warehouse and slice off one of the lasers, and uses it blast the rest. Bulkhead breaks into Lockdown's ship, and tries to attack him, but Lockdown uses a freezing agent to latch him to a wall. Bumblebee tries to chase Lockdown, but he uses Optimus' energy axe to slice open an oil line, which sends Bumblebee careening into a fence. Prowl then lands on top of Lockdown's face in cycle mode before launching off and transforming. They have a small fight where Prowl actually has the upper hand, before Lockdown uses the EMP launcher to knock him out. Ratchet then arrives, demanding that Lockdown step away from the Autobots. Ratchet charges at Lockdown, but he merely blasts him with another EMP blast. Lockdown walks away before being hit by Ratchet's magnet beam, sending him flying into a wall. Lockdown is bewildered before being blasted again. Ratchet then drops a car on Lockdown before revealing to him that his own EMP doesn't work on him.
Ratchet breaks into Lockdown's ship and finds Optimus. While setting him free, the ship goes into a launch sequence. As they try to escape, Lockdown arrives and whacks Ratchet with Optimus' grapple cannons. However, Ratchet uses his magnet beams to crush Lockdown with his own trophy case. He then rips Optimus' grapple cannons put of Lockdown's wrists. Lockdown then begs for Ratchet to use the EMP launcher on him to null the pain, sending Ratchet back into the flashback.
Lockdown is observing Arcee, noting that she has the data he's looking for. As Lockdown walks off, Arcee kicks the EMP launcher off a table and into Ratchet's hands. She begs him to wipe her memory core of the access codes with it, because they are too crucial to fall into Decepticon hands. Lockdown then comes back, and tries to grab the EMP from Ratchet's hands, and he fires it, knocking out Lockdown. Ratchet and Arcee then escape the ship, but Ratchet realizes that Arcee lost her memory anyway.
Ratchet then comes back to the present, and Lockdown tries to whip him when he walks over to grab the EMP launcher, but Ratchet's magnet beams keep him sedated. Ratchet grabs the EMP launcher and fires it at the ship's control panel, and the ship starts to fall to Earth, crashing in a river right after Optimus and Ratchet escape. The final scene shows Ratchet repairing Optimus as he finally starts to open up about his past.