Ratchet's old enemy, the bounty hunter Lockdown, resurfaces.

Blackarachnia confronts Bumblebee and Bulkhead as they are celebrating their first Halloween.

Bulkhead is suspicious of the musical robot player Sari receives as a birthday gift.

Blitzwing and Lugnut come to Earth to help Megatron get the Allspark.

A disgruntled former employee tries to use an Autobot to destroy the city in a bid for revenge.

Starscream, Lugnut and Blitzwing invade Earth; Optimus Prime makes Sari turn over her Allspark key.

The Autobots must rally to prevent the AllSpark from falling into the clutches of the Decepticons.

Optimus teams up with Sentinel Prime in order to defeat the Headmaster.

Unaware of the Decepticon activity, the Elite Guard take Optimus Prime and the Autobots back to Cybertron.

When the AllSpark turns construction vehicles into Autobots, Bulkhead becomes fast friends. However, the Decepticons have other plans in mind.

The second-rate villains of Detroit team up to beat the Autobots.

While chasing an Autobot traitor, Bumblebee thinks back on the time he spent with Bulkhead in the Autobot Boot Camp.

Prowl and Optimus Prime are on the defensive when Lugnut's clones attack Detroit.

One Autobot has suffered severe damage.

Blackarachnia is desperate to find Wasp before the Autobots.

Ratchet is determined to go to the moon to save Omega Supreme.

The Autobots try to warn Cybertron of Megatron's spy.

Megatron and the Decepticons focus on conquering Cybertron.

Sentinel has success in capturing fugitive Decepticons.

The Elite Guard heads back to Cybertron with prisoners.

The Autobots find that their new base on Earth is already inhabited.

A bioengineering genius experiments with some of Bumblebee's hydraulic fluid.

Megatron reprograms Professor Sumdac's animatronic dinosaurs, turning them into Dinobots.

Bumblebee springs into action when Megatron unleashes a speed demon and sends it on a crime spree.

When Sari mysteriously disappears, Prowl and Bulkhead go searching for her on Dinobot Island.