Ant and Fontaine realise their grandparents found Lemuria before them - but where are they now? The Nektons follow the trail they left but run into giant, predatory Sand Strikers! Was this the fate of their grandparents?

Three baby Monumential turtles hatch, and they are the size of city blocks! The playful babies accidentally sink a fishing trawler! Can the Nektons wrangle these creatures before they sink even more ships?