What could top a sleepover in the backyard with Buster and the Brain? As far as Arthur is concerned, nothing! But then rumors start that a spaceship has landed in the neighborhood - and suddenly the idea of camping under the stars takes on a whole new meaning. Arthur's sister D.W. is so sure that he will see an alien on his overnight that she gives him her camera. And when the three boys hear muffled footsteps approaching their tent and see strange flashes of light, it seems D.W. was right! Or was she?