After the events in Peru, the Autobots and Maximals return to Earth with warnings of an ancient, cosmic force — Unicron, the devourer of worlds — who is awakening from deep space. His arrival threatens not only Earth, but all life in the galaxy. With Optimus Prime now fully trusting humanity, he and Noah Diaz (working secretly with G.I. Joe) begin coordinating a global defense. However, Unicron has already sent a new wave of heralds — the Terrorcons and a corrupted former Autobot commander — to prepare Earth for consumption. Meanwhile, on Cybertron, Elita-One, Arcee, and surviving Autobots search for the Allspark’s twin, a cosmic artifact said to be the only thing capable of stopping Unicron. But to use it, they must join forces with the Quintessons, ancient beings who once ruled Cybertron — and cannot be trusted. As Unicron begins merging realities to consume Earth and Cybertron simultaneously, Optimus Primal and the Maximals face off against ancient beast-mode Terrorcons corrupted by Unicron’s essence.
