Eight-year-old Jack, his seven-year-old sister, Annie, and Peanut the mouse ride in a tree house to the Amazon rain forests, where they encounter giant ants, flesh-eating piranhas, hungry crocodiles, and wild jaguars.
After living in fear of the wolf with crazy eyes and fangs like ice picks, a forest community is stunned when he shows up looking calm and wearing striped underpants, leaving them wondering why they were so afraid of him.