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.

Charlie Kenton is a washed-up fighter who retired from the ring when robots took over the sport. After his robot is trashed, he reluctantly teams up with his estranged son to rebuild and train an unlikely contender.