A major hurdle that was overcome during the film's production was the 2007–2008 Writers Guild of America strike, as well as possible strikes by the Directors Guild of America and the Screen Actors Guild. Bay finished the production on time with the help of previsualization and a scriptment by his writers Roberto Orci, Alex Kurtzman, and series newcomer Ehren Kruger. Shooting took place from May to November 2008.
The film opens with a short prologue narrated by the voice of Optimus Prime. It depicts primitive human beings in the year 17,000 BC hunting a tiger, only to be interrupted by the appearance of the Fallen which begins to attack them. In the background, more Transformers can be seen constructing a gigantic device before the scene fades to black.
Two years after the events of the 2007 film, the Autobots have joined forces with the British and American military to form an organization named NEST to combat the Decepticons hiding out on Earth. Optimus Prime leads NEST into Shanghai, China, to eliminate Decepticons Demolishor and Sideways. He is joined by newcomers including Arcee, Sideswipe, Jolt and the twins Skids and Mudflap. Sideswipe kills Sideways with the help of Arcee and the twins, and Optimus and Ironhide kill Demolishor but not before the Decepticon utters that The Fallen will "rise again".
American National Security Advisor Galloway berates the Autobots and NEST for the massive collateral damage they caused in Shanghai, suggesting that the Autobots leave. While Optimus does agree to this if the President of the United States of America commands it, he questions what will happen if the planet is left defenseless. Soundwave, a Decepticon intelligence officer, hacks into a satellite and discovers the location of Megatron's corpse and the location of a piece of the AllSpark, the source of the Transformers' existence. Soundwave deploys his minion Ravage to retrieve the shard, which he succeeds in accomplishing. Deep within the Laurentian Abyss, the Constructicons and a surgeon-robot named Scalpel revive Megatron using the piece of the AllSpark and one of their own sacrificed for parts. Megatron flies to a Decepticon spacecraft where he is reunited with air commander Starscream and The Fallen, Megatron's master. The Decepticons are seen growing hatchling Transformers. However, these die immediately at birth due to insufficient energon, "the life blood" of the transformers. The Fallen intends to destroy the Sun and Earth in the process in order to create more energon.
Sam Witwicky prepares to head off to college, intending to live a normal life. Whilst packing, he finds another shard of the AllSpark which fills his mind with ancient Cybertronian text. The AllSpark fragment burns his hand, and through his room's floor into the kitchen, bringing various appliances to life. The resulting robots are then destroyed by Bumblebee, wrecking the Witwicky family's house in the process.
Sam entrusts the shard to his girlfriend Mikaela, who hides it in her father's safe at a motorcycle garage. Decepticon Wheelie tries to steal it, but is captured by Mikaela and burns out his left eye by using a blow torch. At college, Sam meets his roommate Leo Spitz, who runs an alien conspiracy website, and a girl named Alice who makes disturbing advances on Sam. Sam begins to constantly get outbreaks of seeing Cybertronian text in his mind, and having the urge to write it on everything. After one of such episodes in his astronomy class, he calls Mikaela and she comes to Sam's aid, finding him being attacked by Alice. When Alice is revealed to be a Decepticon Pretender, Mikaela, Sam and Leo drive off, with Alice chasing them. Mikaela, being the car's driver, disposes of Alice, but while on the highway they get carried away by Grindor in his helicopter mode. After Grindor drops them into a building, the trio gets confronted by Megatron, Starscream, Grindor and The Doctor. Sam is then immobilized by Megatron, and as The Doctor prepares to dissect Sam's brain to get information on the location of a new energon signal, Optimus and Bumblebee arrive. Optimus then pursues megatron to a nearby forrest with Sam. Telling Sam to hide, Optimus soon realises it is a trap and is confronted by Megatron, Grindor and Starscream. Optimus takes on all of the Decepticons, killing Grindor and severing Starscreams arm. However, Optimus is impaled through the chest by Megatron and enters stasis lock in a near death state. The rest of the Autobots arrive on the scene and fend off the remaining Decepticons while Sam is evacuated by Bumblebee and the twins.
The Decepticons invade the planet, sinking an aircraft carrier upon their arrival. Soundwave hacks into all television signals to broadcast The Fallen demanding that Sam be surrendered. Meanwhile, Galloway shuts down NEST and Sam's parents are captured by Rampage in Paris.
Sam, Mikaela, Leo, Bumblebee, Wheelie and the twins rendezvous in a remote location to hide Sam. Leo suggests seeking the help of his website rival "RoboWarrior", who is revealed to be former Sector Seven Agent Simmons. Simmons reveals his hidden archive of alien research and explains the history of the Transformers on Earth. It is explained by Wheelie that the language Sam sees is of the Dynasty of Primes, the original seven Transformers who powered the AllSpark like a battery by destroying suns. Wheelie leads the group to Jetfire, an old Seeker who joined the Autobots due to "personal choice". When Wheelie hears Jetfire's reason for changing sides, he too decides to join the Autobots. After getting updated on the situation, Jetfire uses a space bridge to teleport the group to Egypt. Upon arrival, Sam injures his left hand while everyone else is ejected out of the space bridge in different directions. After everyone regroups, Jetfire explains that the Primes used the suns to power the AllSpark by using machines called Sun Harvesters, which uses the Matrix of Leadership as a key. The Primes, however, maintained that the Sun Harvester not be used in a star system with life forms. One of their own — now known as The Fallen — betrayed them, and sparked the war for the AllSpark. The other Primes defeated The Fallen and then sacrificed themselves to seal away the Matrix in a tomb hidden somewhere in the desert.
Through clues, the Matrix is found in Petra but it crumbles to dust in Sam's hands. Nevertheless, Sam piles the dust into his sock. Simmons contacts Major William Lennox and his troops and asks them to bring the Autobots and Optimus' corpse to Egypt so Optimus can be revived, a Prime being the only one capable of killing The Fallen. The military arrive but so do the Decepticons. Leo, Simmons and the twins face off against Devastator, the combined form of several Constructicons, who scales a pyramid to uncover the Sun Harvester. Devastator is ultimately destroyed by a rail gun round fired from a nearby destroyer on Simmons' orders.
Bumblebee rescues Sam's parents, and kills both Ravage and the red Rampage. the red Arcee is killed in the fight. Additional reinforcements are summoned, killing Long Haul, Scrapper, and Hightower. However, Sam is caught in the attack and is severely injured by Megatron; in his unconscious state, he has a vision of the Dynasty of Primes. Sam reawakens, telling Mikaela that he loves her just as the Matrix regenerates, and Sam uses it to revive Optimus. However, before Optimus can be fully revived, The Fallen travels through a space bridge and takes the Matrix back out of Optimus' spark.
After killing Mixmaster, Jetfire fights and kills Scorponok, but is mortally wounded. He thus gives up his own spark and parts to Optimus, which are attached with the help of Jolt and Ratcher. Optimus uses his new strength to destroy the Sun Harvester and kill The Fallen. Megatron and Starscream make a tactical retreat.
The film concludes with Optimus proclaiming that the Transformers and humans now share an untold history and will combine their differences.Here is the trailer!!ENJOY!!!
