2 years after Sam & Mikaela discovered the existing of the Transformers, now working with NEST, a military organization consisting of human troops and his own team of Autobots. During a mission in Shanghai, they knows that the Fallen will be coming and that makes Optimus Prime worried. In the other event, Sam starts seeing the symbol known as Prime Language ever since he touched the fragment of the AllSpark. There we another fragment of Allspark kept in the Nest HQ and was stolen in the same time by Decepticons to revives Megatron. Since Sam know the location of the Energon source so the Decepticons kidnapped Sam.
In the event of getting Sam away from the Decepticons, Optimus Prime was killed. After Prime's death, Megatron orders a full-scale assault on the planet. The Fallen speaks to the world and demands them to surrender Sam. They find former Decepticon named Jetfire, who can translate the language. Once Jetfire was activated and starts to explains that the tomb of the Primes is located in Egypt. Sam and the group locates the Matrix and is the only hope to saving Optimus Prime and he and instructs Simmons to telephone Major William Lennox to bring the other Autobots and Optimus's body.
The military arrives with the Autobots, but so do the Decepticons, and a battle arises. Optimus Prime was revived with the Matrix and all of a sudden the Fallen arrives and took the Matrix to activates the Sun Harvester. During the encouter with the Decepticons, Jetfire was wounded so he merged with Optimus Prime to give him the power to defeat The Fallen.