Greg, the young green alien, has a great time during his first adventure with Gary the Space Dragon. Everything happens in the strange and massive mountains on Planet Roca. This planet is at 1,230 light-years away from Earth and even if it is huge, from your window, it looks like a tiny shiny star. Like all the other aliens who live on Roca, Greg travels in a big flying-saucer that he will use, for the first time, in this adventure.Many other mysterious adventures will follow.