A small, multicolored hippo-like, English speaking animal is befriended by an American family with twin children, living on an island in the Pacific Northwest. Initially concealing it from the authorities, they try to find out what it is and how it talks, with the help of a vet and a zoologist.
Meanwhile the fast learning animal has become computer literate and learned to play chess. After a successful outing with the help of a broadcaster, an institute is set up to study the animal scientifically. Threats from religious zealots complicate this research.