Spark of Darkness is the twenty-third episode of the Beast Machines TV series.
The Maximals celebrate the defeat of Megatron inside the now-dormant Grand Mal. But while most of the group high-five each other, Nightscream mourns the loss of his pet, Savage/Noble. Silverbolt wonders if Megatron is truly defeated, but Primal assures his team that he knows Megatron is dead, thanks to their mutual connection to the Oracle. When Cheetor mentions there's still business to be taken care of, Botanica responds she feels there's another evil on Cybertron.
Cheetor and Nightscream are sent to find the Vehicon generals. Silverbolt and Blackarachnia are sent to assess the dormant Transformer bodies to start the process of getting the sparks Megatron kidnapped to function again. Rattrap and Botanica are assigned to attend the techno-organic orchard. Rattrap, of course, whines about this. As he does this, he moans that he feels his talents are being wasted and he'll be stuck with embarrassing stories to tell his grandkids. Botanica argues that tending the garden is important. The debate between the two heats up, and in their rage, the two Maximals accidentally touch lips. The two quickly agree to completely disregard, forget, and ignore their contact and get to work. Optimus stays in the Grand Mal.
At the shell yard, Blackarachnia tries to put the moves on Silverbolt, but without confirmation that Megatron is truly really dead, he's extremely hesitant to respond to her advances. At this, Blackarachnia finally loses patience, and begins berating Silverbolt for his obsessiveness. She's so focused on Silverbolt that only he notices the large, lumbering monster emerge behind her. The two Maximals run away (cowardly) from the giant, but when the monster hits Silverbolt with gunfire, Blackarachnia fights back with her electric sting. The monster knocks her over, but Silverbolt has had time to recover and attacks the monster with his throwing blades. Eventually, Blackarachnia has the idea to attack the monster using an explosive component from one of the nearby Transformer bodies. The behemoth steps out of the explosion, and the two Transformers watch a strange red spark emerge from the monster as it falls over in defeat. The red glow races away.
In the orchard, while Botanica works, Rattrap scavenges parts of a Motorcycle Drone to see if anything can be made into a useful tool. But suddenly, the deactivated Cycle Drone comes to life and begins to blast the orchard. Botanica, upset about the carnage, transforms and uses her bolts to bring heavy wreckage crashing down upon the possessed drone. The drone flails its body one last time before falling over, no longer inhabited by the glowing red spark.
Cheetor and Nightscream meet with Strika and Obsidian and invite the two generals to join the Maximals. As the two generals debate, Thrust stops by to make it clear that he has no interest in joining with the Maximals and that he believes that Megatron, "The Big M," will soon return. After Thrust leaves, the remaining four are attacked by a damaged but resilient Aero Drone. Nightscream sucks the energy from the drone, but the monster still tries to pull Cheetor over the edge of a nearby cliff. Cheetor is saved by Nightscream and the drone falls, but before it makes impact with the water below, the glowing red spark leaves the body.
The group returns to meet with the other Maximals (sans Botanica) inside the Grand Mal, and Optimus welcomes Strika and Obsidian to the team. The two new recruits leave to fortify the base—just in time for Rattrap to detect the haunting red spark heading right towards them all. Inside, the spark passes by the two generals and briefly encounters Cheetor and Blackarachnia. Next, the spark uses a Tank Drone body to attack Optimus and Botanica. While Rattrap tracks the movement of the Spark, he deduces a way to neutralize its rampage.
Rattrap uses a Spark Extractor on the Tank Drone to draw out the spark. Once the red spark is contained, he "re-polarizes" his captive, but the Spark Extractor flies alive, trying to break free of Rattrap's grip. After escaping the spark extractor, the spark flies into a Diagnostic Drone and, finally coherent, exclaims "I live!" But Rattrap has the next laugh: The spark, who is clearly Megatron, is now trapped inside of the diminutive body.
The Maximals meet Megatron, but he laughs at them. Even in his tiny form, he's able to reactivate the Grand Mal's internal defenses to evict the Maximals. As the Maximals struggle against the tentacles that have begun to bind them, Primal has an Oracle moment, but the Maximals are all captured anyway. Megatron starts to reformat Primal's spark, but Rattrap gets Botanica to destroy the control panel, freeing the team from Megatron's grip.
Obsidian arrives at the fight scene and is forced to choose: Be loyal to Primal's or Megatron's side. The two generals grab Megatron and fall out of sight. Out of immediate danger, Optimus explains that Nightscream didn't kill Megatron, but only turned Megatron into the monster that he was but no longer is.
Away from the battle, Strika, Obsidian and Megatron meet up with Thrust. Enraged that he was pulled out of battle and refusing to accept a withdrawal was sensible, Megatron growls that at least Obsidian and Strika weren't "useless" like Thrust; Obsidian admits that it was Thrust who reminded them that their true loyalties lay with Megatron. No longer in control of the Sparks, Megatron declares, "The time for action is now."