A symbol projected by the Ephemychron leads the Nektons to a mysterious site. Ant is sure that, this time, it must be Lemuria. But, arriving there, the Nektons find only a strange underwater mound. They can see dolphins coming and going from an entrance. They enter carrying seaweed, and exit carrying nothing—very unusual. Entering the mound, the Nektons encounter a maze! And soon, the mound gets even weirder. When the Nektons move carefully forward, walls shift and move—spaces change—and they become disoriented. They’re soon separated from each other and trapped inside! Ant manages to accidentally find his way out and returns to the Aronnax so he can get intothe Mimic Knight and find the others. But when Ant finally navigates through the whole maze,, he finds they and the dolphins are not alone! In the centre of the maze Ant finds a Minotaur! Even stranger than the one of legend, this Minotaur has a bull’s head, a man’s torso and the tail of a shark! It seems angry that humans have invaded its home. When the Nektons manage to find each other, it charges them furiously! Ant realises that dolphins bring seaweed into the maze to feed the Minotaur. If the dolphins can find their way out, maybe by following their lead, the Nektons can too! It’s only when Ant uses the echolocation system of the Mimic Knight that he sees the maze as the dolphins do. Now he can see an opening that was invisible to normal eyes. Using it, the family finally escapes. Afterwards, they speculate that this creature really was the basis of the Minotaur legends—therefore it, and the maze, must be incredibly ancient!