As you probably know from the first Transformers movie, in 2007, Decepticons were ‘the bad guys’. This time, Decepticon forces return to Earth on a mission to take Sam Witwicky prisoner, after the young hero learns the truth about the ancient origins of the Transformers. After returning to Cybertron, Starscream assumes command of the Decepticons.
The Autobots believing that peace was possible find out that Megatron's dead body has been stolen from the US Military by Skorpinox which had revived him using his own spark. Now Megatron is back seeking revenge with Starscream and more Decepticon reinforcements on the way, while the Autobots come to face them with some reinforcements of their own.
As for the Autobots reinforcement casted in Transformers 2, there a couple of surprises for the fans. The Sisters (a pink, a blue and a purple motorcycle respectively) are three Autobots with feminine appearances and personalities. Mudflap and Skids (aka the Twins) are a red Chevrolet Trax and a green Chevrolet Beat. Sideswipe transforms into a silver Corvette Stingray Concept and Jolt (a blue Chevrolet Volt) comes as a last-minute addition to the movie.
The movie directed by Michael Bay, having Steven Spielberg as its executive producer, will hit the screen in June 2009.