Optimus Prime and Ratchet stake out a Vehicon mining operation overseen by Megatron. Optimus isn't about to let Megatron take the unknown object that gave off the signal that led him and Ratchet there. Optimus confronts Megatron just as the Vehicons break through earth and hand the relic to him. Megatron advises Optimus to stow his weapons; the device they've unearthed is a deadly spark extractor, capable of sapping the spark from the body of every Cybertronian in its radius. He takes the opportunity to gloat about how Optimus—ahem, Orion—led him to it before stepping through the Ground Bridge, and ordering the Vehicons to hold Ratchet and Optimus off. Close by, Bumblebee speeds over a cliff and through the attacking Vehicons, before driving into the Ground Bridge. He transforms and grabs the package from Megatron's hand, before turning around and bolting. Megatron runs after him, but upon arriving outside the vortex, finds his troops destroyed and all three Autobots gone.
Back at base, Bumblebee brags about his vehicular acrobatics. Ratchet informs Optimus of the reason for the Autobot homing beacon on the device—it was sealed away in Iacon during the war, but was jettisoned offworld when the Decepticons raided the city. Arcee asks if Optimus remembers if he transcribed any other coordinates, but Optimus regrets that he does not. Ratchet posits that Megatron said he decrypted multiple targets to play havoc with Optimus' psyche.
On the Nemesis, Megatron laments over the loss of the spark extractor, and regrets that he did no more than destroy Bumblebee's voice box back on Cybertron. Soundwave reminds Megatron that there are still two contacts on Earth to investigate.
On the road, Bumblebee sounds off to Bulkhead to rendezvous with him at the coordinates of the new distress beacon. Upon arriving, however, the only device present is an upright beacon. Suddenly, Bumblebee is stunned by a large electrical blast, and he falls unconscious. Silas and a MECH team emerge from the shadows, including a MECH Surgeon who starts work on Bumblebee. Unseen by the troops below, Starscream arrives and transforms on an overlooking cliff. As MECH spots Bulkhead incoming, the surgeon finishes his work, and the team departs in a helicopter. Bulkhead arrives and asks Bumblebee who did it, but Bumblebee doesn't recall. Bulkhead advises pursuit, and transforms to roll—but Bumblebee doesn't. Antsy at the hold-up, Bulkhead asks Bumblebee why he's not transforming, and Bumblebee replies that he can't.
Back at base, Ratchet scans Bumblebee and discovers that his T-cog is missing. The Autobots quickly work out MECH is behind it, and Optimus tells Bumblebee he's going to have to rely on his friends for a while. Bumblebee is very depressed. Optimus is worried about what Megatron might unearth next.
MECH install Bumblebee's T-cog into the robot they've built, but when they power it up and have it scan a helicopter, the robot is unable to transform. Starscream, who has been spying on them, reveals himself and proposes an alliance. He explains the T-cog requires energon to work. He intends to supply MECH with information on energon so they can work out a way to find energon deposits.
Bumblebee is making a pain of himself bugging Ratchet, who asks Raf and Miko to keep him busy. Unfortunately all of their entertainment reminds Bumblebee of his missing vehicle mode. Raf makes another attempt to make Bumblebee feel better, but is undermined by Arcee and Jack racing into the base at high speed. Ratchet has to stop Bumblebee from going out for a walk, but feels guilty at his inability to fix his fellow Autobot. Some time later, Ratchet picks Raf up outside school, much to the boy's discomfort.
On monitoring duty, Bulkhead detects a signal, and Bumblebee insists on going with him to investigate.
Raf asks how Bumblebee's voice box was damaged, and Ratchet tells how Bumblebee was captured at Tyger Pax and given a working over by the Decepticons. Though a field medic saved the scout, it wasn't enough to save his voice box.
Bulkhead and Bumblebee track the signal to a cave. Knock Out soon comes barreling out, closely followed by Breakdown. While Bulkhead tackles the latter, Bumblebee attempts to chase Knock Out on foot. He soon finds he can't even transform his arms to deploy his guns, and is forced to continue the pursuit by using an old truck as an impromptu go-kart. Unfortunately it loses a wheel, and as Knock Out speeds off with the pilfered device, Bumblebee is sent flying off a cliff.
- Rafael Esquivel
- Jackson Darby
- Miko Nakadai
- William Fowler
- Leland Bishop
- MECH Commandos
- MECH Surgeon
- Sierra's friend
- Starter Guy
- In "Darkness Rising, Part 2", Agent Fowler refers to Bumblebee as a custom muscle car, but in this episode he is revealed to be an apparently-uncustomized Urbana 500.
- Though Ratchet has standard vehicle instrumentation, the needles don't move, at least while they're in shot. His speedometer is showing a higher reading as they slowly move away from the school than later when they're driving down the street.
- When Optimus draws his weapon at the start of the episode, he draws his left cannon. When he charges Megatron he's then wielding his right cannon.
- When Jack drives Arcee into the Autobot Base and puts his foot down, it disappears through the floor.
- Again, Optimus Prime/Orion Pax is referred to as an "ar-KIVE-ist," this time by Bulkhead.
- Bumblebee's car mode is revealed as the Urbana 500.
- This is the first time a fight has happened inside the Ground Bridge. Seeing as it's quite long, this may explain how in other episodes, characters sometimes exit the Ground Bridge in a different order than they entered it.
- Bumblebee, Ratchet and Starscream's Cybertronian modes, again, have Earth vehicle kibble.
- The title is a nod to a Season 1 episode "Operation: Breakdown".
- It was revealed that several artifacts were jettisoned into space during the war, explaining why earlier devices were found on Earth.
- Bumblebee's door wings move with his emotions just like with Starscream. They act like animal ears.
- Optimus has finally been repaired from the damage he got in his battle with Megatron in "One Shall Fall".
- Project Chimera's fingers and right shoulder armor look very similar to Optimus's.
Main Article: Operation: Bumblebee, Part 1 Gallery
Operation Bumblebee, Part 1}}