Transformers 2: Rise of Unicron

Transformers 2: Rise of Unicron is the 2009 sequel to Transformers: Robots in Disguise.

Plot
Since Megatron's defeat, the Autobots have formed an alliance with the humans to create MECH, an elite top secret task force hunting down the Decepticons who have remained on Earth. During a mission to Shanghai, Autobot leader Optimus Prime battles a Decepticon named Demolishor and fatally wounds him. However, before he dies, the Decepticon warns Optimus of the return of Unicron, the legendary destroyer.

The Decepticon Soundwave, eavesdropping on a conversation between the humans and the Autobots, learns that a shard of the One is being held at the MECH base and sends Ravage to steal it.

Back in the US, Daniel Witwicky is preparing to leave for college, leaving his girlfriend Carly Spencer and guardian Bumblebee behind. Unbeknownst to him, while packing, he comes across an old t-shirt that he wore the day of the battle of Mission City. A piece of the One then falls into his belongings and he takes it with him to college. After arriving, he meets his new roomate, Carlos Lopez, who runs a conspiracy theory website about the existence of the Transformers.

Daniel is later picked up by Bumblebee, who takes him on a drive to meet with Optimus. Optimus asks Daniel to appeal to the US Government for him as they are worried about the damage the Autobots are doing. Daniel refuses, telling him that he is not part of his war, but Optimus warns that he may soon be. Meanwhile, the Decepticons dive the Laurentian Abyss and ressurect Megatron. Megatron returns to the Decepticon flagship, the Nemesis, and is reunited with Starscream. He is about to kill Starscream for leaving him to die on Earth when he is halted by Unicron, who has taken over leadership of the Decepticons. Unicron reveals that he must destroy Optimus Prime, the only one capable of destroying him, as well as steal the Autobot Matrix of Leadership, which has been missing for eons, as it is instrumental to his mysterious plans.

At her home, Carly is attacked by the tiny Decepticon Wheelie but manages to trap him inside of a safe. She then meets up with Bumblebee and they head for Daniel. Meanwhile, Daniel gets into a fight at a party and gets both himself and Carlos kicked out. As the two argue, Starscream appears and chases them into a warehouse. As he pins Daniel down, Bumblebee bursts through the wall and tackles him, then alerts Optimus. Optimus arrives and Bumblebee escapes with Carly and Carlos but they become seperated from Daniel as the battle spills over into the forest. Megatron and Soundwave then arrive and Optimus takes all three on. He defeats Starscream and decapitates Soundwave, but Megatron impales him from behind and shoots him through the chest as Daniel watches. He is then picked up by Bumblebee as the Decepticons leave the scene.

Megatron launches a full scale assault on the planet in the wake of Optimus' death. Unicron uses a hijacked satellite to broadcast a message to the humans, demanding that they turn over Daniel or the attacks will continue. Now fugitives, Daniel, Carlos, Carly and Bumblebee try to move about discreetly. Carlos says that they may find help in his online rival, RoboWarrior. This turns out to be none other than Seymour Simmons, the former government agent from the first film. Simmons tells them that the only one who may known what Unicron is planning is Jetfire, an ancient Decepticon who lays dormant in the Smithsonian. The group infiltrates the mueseum and reactivate Jetfire, who reveals that he has defected to the Autobots. Jetfire takes them to the Egyptian pyramids, explaining that many many years ago, Unicron was the leader of a group of Cybertronians who were trying to harvest Energon from the suns of planets, with the one rule that they would never claim the sun of a planet with life on it. Unicron tried to steal the Earth's sun but the others rebelled and imprisoned him. He has now returned to finish the job but requires the Autobot Matrix to activate the Solar Harvester. The group search for the Matrix and Daniel finds it. He then has Simmons summon MECH to their location, along with the body of Optimus.

MECH soon arrives, but so do the Decepticons. A battle breaks out in the ruins while the Decepticons Devastator arrives and unearths the Solar Harvester, hidden in the peak of one of the pyramids. Jetfire is fatally wounded by Ravage, who he then destroys. MECH launches an air strike on the Decepticons, destroying alot of them. Daniel then plunges the Matrix into Optimus' spark, ressurecting him. However, Unicron then appears and steals the Matrix. The other Autobots turn their fire to Devastator and destroy him. However, they are too late to stop Unicron from activating the Solar Harvester. Jetfire sacrifices himself to transfer his parts to Optimus, empowering him. Optimus fleis towards the top of the pyramind and manages to knock Megatron off before grappling with Unicron. Optimus manages to break the top of the Solar Harvester off and stab Unicron through the head with it, his body falling into the machine and Optimus dives to safety. The harvester explodes, killing Unicron for good. Suddenly, Optimus is attacked by Megatron. Megatron gains the upper hand until Optimus grabs the Matrix and weakens him. He then blasts Megatron's face apart, tears him arm off, and hurls him through a wall. Optimus returns to his allies side in the aftermath of the battle as Megatron and Starscream flee into the desert. He announces that the humans and the Autobots will from now on have a better working relationship as MECH and Daniel tells Carly that he loves her.