Paul McCartney is authoring a children's picture book about a squirrel and a frog who save animals, dpa reported. The 62-year-old has been working on the story for "High in the Clouds: An Urban Furry Tale" for years. The book is due out in October with an initial print run of 500,000, Penguin publishers said Thursday. McCartney is being helped by children's author Philip Ardagh and illustrator Geoff Dunbar, Penguin said in a statement. The story for the book was inspired by the animated film "Tropic Island Hum", on which Dunbar and McCartney collaborated. "Having worked on this story and the characters for many years, it's very exciting for me to see things come to fruition in what I think will be a remarkable book," the publisher quoted McCartney as saying. --SP 0001 Local Time 2101 GMT