If you have followed the movie since it's first release, you'll understand the Age of Extinction. It's about the government eradicating the existence of the Bots but the thing is that the the division holding it has something not on the book, and that is working with Lock Down, a non Autobots or Decepticon that I think is working for Unicron. Overall the movie is great, effects are better, acting is better, plot is more mind twisting. Definitely watch it, worth your hundreds. :)