Dexter's made the most amazing discovery known to Planet Earth – alien life! Unfortunately for the boy genius, his archrival Mandark has made the same discovery. But soon both boys learn that this alien has only one thing on its mind – or rather, its stomach – and that's eating the smartest brains it can find. Now, for the first time in his life, Dexter actually wants to prove that Mandark is smarter than him. But is he clever enough to pull it off?