Ernest, Franz and Marie hike to the north side of the island to search for a wedding anniversary present for their parents. They find a chest from their shipwreck which may contain a valuable artifact.
Ernest and Franz rescue a castaway they find floating offshore on a couple of barrels. The castaway says he has a map of the island, and insists that there is a settlement beyond the waterfalls.
Mother prepares an oyster stew for the family, but they're inedible. As she's tasting the meal while cooking, she consumes enough poison to collapse and fall into a coma.
Franz and Ernest find an abandoned pirate camp while exploring the island. Franz also finds a treasure map at the camp, and becomes obsessed with finding the treasure, while neglecting his usual duties.
Johann cancels lessons when Ernest, Franz and Marie complain that school is useless on the island. But when Johann tells them they can have two days to do whatever they want, they find out that math and science can be useful after all.
