Nine-year-old Phineas William Walsh has an encyclopedic, obsessive knowledge of the natural world. He knows that rockfish have swim bladders that can burst and push their intestines out their butts, and he knows that barnacles have the longest penises in the animal kingdom. What he doesn’t know is why his granddad had to die or why Lyle the bully always picks on him or why his parents can’t live together. Or why he has to go see a psychologist. Of course he’s worried sick about what humans are doing to the planet — shouldn’t everyone be losing sleep over it? After all, when other animals are threatened, they don’t just sit there — they react. So, when his fourth-grade class gets a pet frog, Phin is spurred to action.