A year into their mission with the children of the Resolute, Judy, Penny and Will scramble to find the titanium they need to get to Alpha Centauri.

While Judy sets out to find Grant Kelly, Penny and Will explore a mysterious tunnel. Light years away, Maureen, John and Don hunt for SAR's remains.

Scarecrow helps Maureen and John plot an engine heist. Judy returns to camp with new passengers. Will makes a startling discovery in the alien city.

As the adults race to destroy all clues to the location of Alpha Centauri, the Robinson kids receive an ominous message from SAR.

The story of Don's run-in with SAR leads the Robinsons to an alarming realization. Will sneaks out on a dangerous solo mission.

The Robinsons race to get help for Will, warn the other colonists and activate a secret defense system. Vijay tags along with Penny on a risky outing.

As the battle for Alpha Centauri unfolds, the Robinsons and their friends risk everything to restore peace and pave the way for a better future.