Dennis and his faithful hound Gnasher are out to make every day as much fun as possible, but their adventures often lead them into trouble. Gnasher has a crisis of confidence when 'the world's greatest dog' comes to town, Kutta - a dog astronaut who has just orbited the Earth as part of a special Space programme. Dennis and co resolve to get the old Gnasher back by going one better; they make a plan to menace up a spaceship and spirit Gnasher away to the 'moon', to meet an 'alien' and return a hero... of course it doesn't quite go according to plan, and when the menaced up spacecraft goes out of control Gnasher must find his mojo in order to save the residents of Beanotown for real.
