Fires of the Past is the third episodes of the Beast Machines TV series.
A fleet of Vehicon Tank Drones roll towards the Cybertron Archives. A hiding Blackarachnia watches in horror as the tanks open fire, seemingly without provocation, on a statue of Optimus Prime holding a pair of Golden Disks. The tanks continue their barrage on the Archive center itself as Blackarachnia runs back to the rest of the hiding Maximals, who are there searching for clues to what happened to the missing Cybertronian population. Rattrap makes it out of the Archives, revealing that he's found... absolutely nothing. The Archives have been deleted in their entirety.
Optimus Primal howls in rage, while a spying Megatron chuckles to himself that he's starting history over; everything prior to his reign is now simply a rumor. Inside Megatron's control chamber, a Diagnostic Drone assures him that he has been "purged" of whatever organic traces remained in him that caused his outbreak into beast mode in the previous episode. More Tank Drones appear to attack the Maximals, and Optimus orders yet another retreat. During the battle, Blackarachnia is knocked out by a blast and has a vision of a beautiful sunset-lit Amazon forest, falling into a pit, and being saved by a shadowy silhouette of Silverbolt.
In the waking world, Cheetor is carrying the woozy Blackarachnia away from the battle while Optimus draws the majority of the tank fire. Rather than simply taking cover behind a building, he climbs straight up one while dodging more shots, and the accumulated damage causes the building to topple on the Tank Drone fleet, destroying almost all of them while Optimus leaps to safety. (Optimus planned it that way. Seriously.)
Megatron is so enraged at this turn of events that he loses all control and again reverts to his dragon form, disconnecting from the control armor. He becomes further enraged when he realizes he still hasn't been cured of his beastial tendencies and takes it out on the Diagnostic Drone with some fire breath. Collecting himself and returning to robot form, he ponders why his elite army of drones is still unable to capture four rogue Maximals. The only reasonable answer is simply "free will", so, Megatron pulls out three sparks from an enormous bank of stored sparks...
Back at the Maximal hideout, Optimus chews out the rest of the Maximals for their extremely sloppy battle performance. Blackarachnia has another vision of Silverbolt while pretending to listen to Optimus' angry lecture. Afterwards she decides to sneak off to the Central Spaceport, and Rattrap has decided to tag along with her. Before Rattrap can get her to explain why she's out there in the first place, they are attacked by three Vehicons. Unfortunately, these three are no Drones—each Vehicon has a spark of their own! They are Jetstorm, a wisecracking Aero Drone General, Thrust, a smoldering Cycle Drone General, and Tankor, a Tank Drone General, whose only distinguishable personality traits are being very angry and stupid.
The three Vehicons pretty much blow up everything around Rattrap and Blackarachnia, completely outclassing them (as newly-introduced Transformers typically do). Blackarachnia loses concentration, reverts to beast mode and she and Rattrap scurry off. Neither of them yet realize it, but doing so saves them—the Vehicons are unable to detect them on radar while in beast mode. Getting inside the spaceport control building, Blackarachnia accesses the aerospace records, finding the records of the Autobot shuttle they came to Cybertron on. She discovers that the ship was shot down by Cybertron's own automated defense systems and that there were six of them on the ship, though their memories of the missing two Maximals are hazy. Blackarachnia then plans to get to the ship itself to find its own backed-up data files.
The Vehicons again attack, having locked onto Blackarachnia's Maximal signature, and she and Rattrap are again forced to flee, with Blackarachnia heading for the Autobot Shuttle and Rattrap simply heading home (he's had enough of being shot at for one day). Rattrap finds out (by happy accident) that the Vehicons are unable to track him while he is in beast mode. He scuttles off to warn Blackarachnia. Megatron decides to call off the Vehicon attack once he realizes where Blackarachnia is headed, so he can tap into her mind when she accesses the Autobot ship's computer and find the Maximal base through her.
Rattrap warns her of this as well, and the two are forced to destroy the shuttle computer to prevent Megatron from finding out the location of their hideout. The Vehicons resume their attack, and Optimus Primal and Cheetor save the day, Batman-style, by crashing through a skylight and fending off the Vehicons long enough to get out of there before the rest of the Autobot Shuttle blows up. Optimus is, in a word, steamed that his teammates endangered themselves needlessly and got their only chance at easy answers destroyed, but nothing can be done about it now, and they all run back to their hideout.