When Bat Pat, a talking bat who lives in a cemetery and writes scary books, spots a suspicious caped figure, he is attacked by a crow and rescued by the Silver family, who help him search for a treasure with the aid of a ghostly sea captain.

Bat Pat and his friends travel to the Arctic and face off against a mad scientist in order to save the last mammoth on earth.

"A Leo le acaban de dar una noticia de miedo: a partir de ahora, y por orden expresa del médico, tendrá que apuntarse a hacer deporte después de clase. Lo que nadie le ha dicho todavía es que, además de sudar como un pollo, en los entrenos hará unos amiguitos de lo más horripilante." --From publisher's description. When Leo's doctor tells him that he has to participate in afterschool sports to get into better shape, things are even more horrifying...