Boundary: Castaway Books in Order

Castaway Planet, Castaway Odyssey, and Castaway Resolution take the larger Boundary universe and shift the focus from interplanetary politics to survival at ground level. The trilogy begins when Sakura Kimei, her family, and their Bemmie friend Whips are torn away from the colony voyage to Tantalus and forced down onto a world that looks like rescue at first, then proves far stranger and more dangerous than anyone hoped.

The heart of the series is the Kimei family. These books care about parents, children, loyalty, fear, and the exhausting practical work of staying alive when every careful plan has already failed. Sakura often carries the emotional center, which gives the story a slightly younger, more immediate feel than the main Boundary novels, but the stakes are no smaller for that.

It is a castaway story in the literal sense.

Once the survivors are stranded, the questions pile up. Is the planet really safe? What already lives there? What pieces of alien technology can be trusted, repaired, or understood? Every gain in shelter or knowledge comes with another reminder that they are very far from home and standing inside someone else's history.

Because it grows out of Boundary, the trilogy still has the same interest in science, discovery, and problem-solving. But it is more intimate. The danger is closer, the resources are thinner, and the emotional center is less about institutions than about a handful of people trying not to lose each other.

If you want the part of the Boundary setting where exploration turns into endurance, this is the branch to read. Start with Castaway Planet and stay with it in order, because the three books are really one long struggle to turn disaster into some kind of future.