In this third book, Zita the Spacegirl is imprisoned and sent to the mines to hunt for a crystal that could lead to the warden's plan to invade the Earth, or Zita's way to go home.

But when her escape attempts fail, she starts to lose hope; until hope returns, in the form of the friends that she had made in previous adventures who all gather to free her, including one unexpected friend. But Zita herself is not through rescuing others.

In the end, it all works out, but is this the final adventure of Zita? Only time will tell.