Space invaders

Since the moment when Amp, a troublesome but friendly alien, crash-landed in his bedroom window, Zack McGee has grown fond of his new friend. They've gotten into a lot of trouble, but they have always been able to invent their way out of it--until now, it seems. Now, a fleet of ships from Amp's home planet have invaded, and it is up to Zack and Amp to save the Earth.