The whole situation began when Duncan Dougal was hiding out in a dumpster (it's a long and smelly story). Stuck in the garbage, he discovered proof that even though the kids drove off the alien named Broxholm the year before, there is still an alien-in-disguise working as one of their 7th grade teachers! But which teacher is it? That's the mystery Duncan must solve to protect the school - and himself.The situation is made harder by his reputation. All his life Duncan has been seen as the bad kid, the mean kid . . . the dumb kid. But his heart is better than people understand . . . and something truly extraordinary is about to happen to his brain.