Earth has been destroyed by aliens called the Axane. Before that happend a group of people were able to get a spaceship called the Moonwalker and escaped. The Axane are still after them but they don't know why. 

Of course they occasionally stop on planets just to get more food and fuel but the aliens on the planets can be a bit cranky. The aliens might try to kill them but that doesn't mean they will,right? Right?