Autobots and Decepticons are at war, with humans on the sidelines. 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. (IMDb)
The plotting is either incomprehensible or downright cheesy (or both–see the climax at Stonehenge with the staff of Merlin), character movements are difficult to make sense of (see Duhamel’s Colonel and co. chase, then join forces with their target; the Earl suddenly ditching), and besides that, it just goes on too long. The action’s good though, and some surprising and genuinely funny moments of levity (see Merlin’s opening plea; Cogman’s organ playing; Agent Simmons in Cuba) help break it up.