Ella, Tilly, Slippy and Madhu are playing a game on the moon when it starts to rumble. The ground cracks open and they fall into what they discover is a large network of tunnels underground.  Because their exit is blocked, they need to find a different way out.  Slippy tries to bore their way out, but he is no match for the moon rock.  They race through the tunnels looking for an exit and, in the process, lose Madhu. Only when they stop to think and come up with a new plan do they find Madhu and a way out.

The year is 3021. The place is the Milky Way, where eight-year-old Ella gleefully heads out with her friends on exciting adventures of discovery. At only eight, she already knows quite a bit about space... but there is always more to explore!