Humans and Transformers are at war. Optimus Prime is gone. The key to saving our future lies buried in the secrets of the past, in the hidden history of Transformers on Earth. Saving our world falls upon the shoulders of an unlikely alliance: Cade Yeager; Bumblebee; an English Lord; and an Oxford Professor.

The quiet life of Baker Dill, a fishing boat captain who lives on the isolated Plymouth Island, where he spends his days obsessed with capturing an elusive tuna while fighting his personal demons, is interrupted when someone from his past comes to him searching for help.