GranPa and Zoe live peacefully on their ranch in the middle of the Australian desert. After a night spent observing the stars, they start a beautiful day with a radiant sun which leads them both to talk about light, its nature and its behaviour. But very quickly this explanation is disturbed by a strange event: the light is fading. It seems that something is masking the sun.

To understand what is going on up there, GranPa decides to take out his old ship and go to Hubble. The famous space telescope allows them to observe the star and see that a strange cloud of gas blocks its rays, and in the middle of this gas a huge machine releases this gas. GranPa immediately guesses who is behind it: Bogbog, his old enemy, an ungrateful teenage alien who enjoys torturing the Earth as if it were a game.

After some misadventures, the two heroes manage to penetrate the machine. Their goal: to get to the heart of the machine to deactivate it. To do this, they must overcome the security systems in place. Three tests await them which oblige them to apply their knowledge on the light. When they arrive at the heart of the machine, they reverse the process. The machine then starts to suck in gas and explode, forcing the two heroes to flee. Bogbog has failed. GranPa and Zoe return to Earth, ready to pick up the day where they left off.