No one knows much about Mer, the underwater kingdom where Mermin the Merman was born, but due to a rising conflict with the people of Atlantis, Mermin is needed back home immediately. Which means that his human friends get to accompany him and see all the aquatic wonders of Mer. But once again, Mermin is tight-lipped about his past - even when it's swimming right in front of him. And there are enemies lurking in the seedier depths of Mer who've got their sights set not only on Mermin, but on Pete and his friends!