Searching for a vital part of the ship that was lost during their crash-landing, Cosima and Big Lizard find Dunk stuck on a beach. They use science to save the day and make a new friend.

Dad drops an essential gizmo in a hard-to-reach place. Big Lizard takes them on an underwater adventure to meet Ammon, the tentacled solution to their problem!

Whilst searching for new discoveries, a rockfall traps Dad, Cosima and Big Lizard in a cave. Just when all is lost, Dad finally discovers a new species!