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, the boys are captured by the humongous hamster hosts during a sightseeing trip to the Great Wheel of the Andromeda Galaxy. Harry and Colin are imprisoned as the school pets, bundled into a human-sized cage and forced to run on a giant 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.