Nine-year-old Phineas William Walsh has an encyclopedic knowledge of the natural world. He knows that if you wet a dog's food with your saliva and he refuses to eat it then he's top dog, and he knows that dolphins can sleep half a brain a time. What he doesn't know, though, is why his grandfather died, or why waste-of-flesh Lyle always picks on him. Or why his parents can't live together - after all, when other mate-for-life animals have a fight, it's not like one of them just packs his bags and leaves the country. To make it to-infinity worse, he's worried sick about what humans are doing to the planet, andhis mother is worried sick about him. But shouldn't everyone be losing sleep over the fact that a quarter of all Earth's mammals are on the Red List of Threatened Species? So, when a White's tree frog ends up in an aquarium in his fourth-grade classroom, it's the last straw, and he and his best friend, Bird, are spurred to action.