A descendant of the Viking raiders, Eric Red, seizes both April and Professor Swenson's map to the underground volcanos in Scandinavia. He plans to tap into the molten energy, melt the polar ice cap and flood the world's coastal cities, making them easy prey for his wanna-be Vikings. The Turtles battle Eric's ""Hammer of Thor,"" fight a mechanical sea serpent and stop the guy before he blows up the volcanoes.