The story of how the government's attempt to stop Depression-era criminal legends John Dillinger, Baby Face Nelson and Pretty Boy Floyd transformed J. Edgar Hoover's FBI from a powerless agency into the country's first federal police force.

The battle for Earth has ended but the battle for the universe has just begun. After returning to Cybertron, Starscream assumes command of the Decepticons, and has decided to return to Earth with force. The Autobots believing that peace was possible finds out that Megatron's dead body has been stolen from the US Military by Skorpinox and revives him using his own spark. Now Megatron is back seeking revenge and with Starscream and more Decepticon reinforcements on the way, the Autobots with reinforcements of their own, may have more to deal with then meets the eye.

Security guard Larry Daley infiltrates the Smithsonian Institute in order to rescue Jedediah and Octavius, who have been shipped to the museum by mistake.

When California girl Susan Murphy is unwittingly clobbered by a meteor full of outer space gunk on her wedding day, she mysteriously grows to 49-feet-11-inches tall. Alerted to the threat of this new monster, the military jumps into action and Susan is captured and secreted away to a covert government compound. There, she is renamed Ginormica and placed in confinement with a ragtag group of other monsters.