From what I can tell, some evil Decepticons landed on the moon and we found them in the 60s moon landing, giving us a tech boost (cause it's not like humans can figure out how to innovate by ourselves!) and now the Decipticons are coming to invade us again.
Okay, it's not a BAD outline. In fact, neither the first nor second movie had a 'bad' outline. The failure is in execution and a poorly disguised contempt for the source material.