Luckily, or unluckily, Jan and Stinky are washed overboard off the coast of Venezuela. Jan and his bro are happy there in the jungle. Jan goes fully Tarzan at this point, but he's already had his head start on humanity, so he winds up learning to use weapons stolen by the Irara, a mysterious goblin tribe. A curious and gifted young man, he explores the jungle. Then two important things happen to Jan. He meets a girl, Ramona, who it turns out eventually is a Siren Princess and the last of her screwed up royal kind. Actually, he rescues her from a Jaguar, which always makes a good impression. They become secret pals and he helps to complete her education, teaching her to read and showing her books.
And he discovers a lost world. Originally, its just a quick visit. But then Stinky gets terrified by a python attack, and flees headlong into the jungle, straight into the lost world that Jan has discovered. So there's nothing for him to do but follow him like a dutiful sibling, which leads to a new round of adventures, just as the whole Jungle man thing was beginning to flag.