The Trigger is the sixteenth and seventeenth episode of the Beast Wars TV series.
An earthquake on a snowy mountainside raises questions from the nearby Tigatron, on his way to file his weekly report with the rest of the Maximals. Rattrap answers Tigatron's call, and as soon as Tigatron mentions that he hasn't seen any Predacon activity, Waspinator and Terrorsaur attack, their attacks causing Tigatron's communication console to collapse upon him as Rattrap listens. Optimus Primal heads out to rescue his comrade.
Tigatron, pushing the console off himself, continues to fight against his airborne assailants. A missile from Terrorsaur is detonated by a shot from Waspinator, tearing the ground into pieces and dropping Tigatron into a cloudy chasm. But when the two fliers follow Tigatron into the cloud to gather his remains as trophies, they are blasted by something unseen.
Primal eventually arrives at the site of the battle, and using Tigatron's communication console, radios to the Axalon that Tigatron is missing, possibly destroyed.
Inside of the cloud Tigatron fell into, the two Predacons discovered Tigatron had landed on a massive flying island. While trying to finish Tigatron, the two were blasted away by energy beams from a strange tower in the center of the island. Megatron sends the team of Scorponok and Blackarachnia to claim the island in the name of the Predacons.
Airazor reports to the Maximals her observation of the two Predacons, who were in much worse condition than they should be had they won the battle against Tigatron, which means the tiger could still be alive. Cheetor rushes in to follow up her report with news that Blackarachnia and Scorponok are leaving the Predacon base. Airazor is sent to follow the two.
In beast mode, Tigatron explores the island he's discovered, and is amazed at the flora and fauna on the isolated paradise. But, after passing a rock with strange markings, the island reveals some strange defenses against his presence. Tigatron decides to play it safe for the rest of his time in the strange area.
Outside of the cloud, Blackarachnia and Scorponok find the island. Scorponok explores the island with one of his cyberbees, until Tigatron snatches the bee out of the air. The deceptive nature of the cloud confirmed, Blackarachnia fires a line into the cloud to board the island. As the line retracts, pulling up the two arachnids, Scorponok sees Airazor in pursuit. Using one of his rockets, he blasts her out of the sky. After Scorponok dodges the island's response to his attack, Blackarachnia resolves to take control of the island for herself.
Tigatron aids Airazor and explains to her that he reprogrammed the cyber bee to carry a message back to the Axalon. Soon, Primal recovers the bee and receives the message explaining how if the island's weapon is commandeered by either side, it would ensure victory….
On the floating paradise island of unknown origin, Tigatron resolves to be the island's dedicated defender, protecting it from the Predacons who would abuse its power. With the injured Airazor on his back, he gets moving. Meanwhile, the Predacons plan to make Tigatron's fear come true. Blackarachnia deduces how to detect traps on the island and that the obelisk that fires the laser weapon must be where the island is controlled.
At the same time, Optimus Primal (with Rattrap on his back) flies towards the island, maintaining radio contact with Rhinox on the Axalon's bridge. Cheetor rushes onto the scene again, as he's spotted Waspinator and Terrorsaur leaving the Predacon base. As soon as he receives the news over the radio, Primal gets into an aerial scuffle with the two fliers, and because of his handicap from carrying Rattrap, is soundly blasted. Primal and Rattrap free-fall out of control.
Rattrap, falling to his death, transforms and blasts the taunting Terrorsaur, commandeering the pteranodon as his new mode of transport. The battle between Primal and Waspinator ends in Waspinator's usual fashion.
Airazor and Tigatron have trouble with another of the island's deadly traps, but Tigatron cleverly blasts his and Airazor's way to freedom. Out of danger, they rendezvous with Primal and Rattrap (who is abandoned by his steed). Tigatron fills in his allies on how the symbols around the island denote the location of traps. Rattrap speculates the function of the island is, in fact, a test of the survival capabilities of whomever visits it.
Blackarachnia and Scorponok reach the obelisk that controls the island. Seeing the fliers, she fakes aggression against them so they attack her, which triggers the island's laser defense, giving Blackarachnia the chance to blast her way inside of the obelisk safely. The black widow marvels at the power of the alien technology she discovers inside. She gleefully announces her plan to use the island to win the Beast Wars for herself. Scorponok objects, but is quickly tricked into one of the island's traps.
Inside of the ornate control room, Blackarachnia steps on a strange symbol on the floor, which bathes her in light. The light alters her colors and her voice and gives her mind a direct connection to the island's power. She blackens the sky and uses the obelisk to rain destruction on the island (in a literal sense). The monolith elongates as she directs the island towards the Maximal base. Optimus radios to Rhinox the command for the crew to evacuate the Axalon.
Rattrap's leg is pinned down by some heavy stone debris, but he commands Tigatron to leave him behind so the cat can stop Blackarachnia's chaos. As Tigatron presses forward, Rattrap uses an energy weapon to get the obelisk's defense beam to free himself. Inside the obelisk, Tigatron reluctantly destroys the island's reactor, knowing that this action will doom the paradise.
Without an energy source, the island loses altitude and guidance, narrowly swooping over the Maximal base. The island crumbles as it crashes into the ground, robbing Blackarachnia of her chance to dominate. The fallen obelisk sends one final pulse of energy into the sky, which bounces off of a similar obelisk on the smaller of the planet's two moons, then vanishes into space.
Tigatron knows the beam was a signal, telling the creators of the island how the Maximals and Predacons ruined their island paradise. A reoccurring butterfly symbolically dies. The Maximals wonder what's next, and how the builders of the island will react to the vandalism.