When the spacebin lands on a strange planet where hamsters have developed into the dominant life form, Harry and Colin are in for another adventure. Unfortunately, some hamster students from the local school decide they want Harry and Colin to be their new pets. The boys are placed in a human-sized cage, complete with a giant running wheel. Things go from bad to worse when the school's laziest hamster is charged with looking after Harry and Colin for the holidays. Will the adventurers find a way to escape from their hamster hell? This book is the third installment in the Cosmic Colin saga.