Being cut off from all her friends in some old asteroid base isn’t Luna’s idea of fun, and having to babysit her younger brother doesn’t add to her enjoyment.

When the base is attacked, the terrified siblings retreat into the pitch-black corridors of the sprawling facility as the unknown assailants hunt them down. With the bad guys closing in, Luna and Rufus fling themselves into space on a battered rocket sled, not knowing where their parents are or who they can trust.

Joining up with their combat pilot grandmother and honorary uncle Simeon Smythe, the teenagers soon discover that their parents unearthed a valuable artifact on a remote asteroid…and have been kidnapped by a ruthless criminal gang who want the artifact for themselves. As does Vernon Voight, the wealthiest man in the solar system.

As Luna and Rufus slowly unravel the true nature of the artifact, they realize that they are running out of time to save not just their parents, but humanity as well.