After Mina's departure, Maude throws herself into solving a puzzle that she's certain will give her the answers she longs for regarding her daughter's disappearance. In the meantime, Bob finds himself at odds with those who've taken charge of the new city. He does what he can to help New Waldoff, but the growing hostility among the Moon Travelers raises concerns over whether history is doomed to repeat. On the Darkside, Fred explores a series of tunnels with a couple of unlikely companions. While hoping to find his way out, he learns more about the moon's history than any Moon Traveler has ever known. This knowledge has the power to change everything, but Fred will have to decide how he wants to use it. For now, the only thing he's sure of is that he has to get Mina back.