Sam Witwicky leaves the Autobots behind for a normal life. But when his mind is filled with cryptic symbols, the Decepticons target him and he is dragged back into the Transformers' war.

Young teenager Sam Witwicky becomes involved in the ancient struggle between two extraterrestrial factions of transforming robots – the heroic Autobots and the evil Decepticons. Sam holds the clue to unimaginable power and the Decepticons will stop at nothing to retrieve it.

Optimus Prime finds his dead home planet, Cybertron, in which he comes to find he was responsible for its destruction. He finds a way to bring Cybertron back to life, but in order to do so, Optimus needs to find an artifact that is on Earth.

After the battle between the Autobots and Decepticons that leveled Chicago, humanity thinks that all alien robots are a threat. So Harold Attinger, a CIA agent, establishes a unit whose sole purpose is to hunt down all of them. But it turns out that they are aided by another alien robot who is searching for Optimus Prime. Cade Yeager, a "robotics expert", buys an old truck and upon examining it, he thinks it's a Transformer. When he powers it up, he discovers it's Optimus Prime. Later, men from the unit show up looking for Optimus. He helps Yeager and his daughter Tessa escape but are pursued by the hunter. They escape and Yeager learns from technology he took from the men that a technology magnate and defense contractor named Joshua Joyce is part of what's going on, so they go to find out what's going on.