Paul McCartney has written his first children’s picture book.

“It’s called ‘Hey Grandude!’ ” said the pop-music legend, 76, last month in a video from publisher Puffin Books. “Why? Well, I’ve got eight grandchildren and they’re all beautiful, and one day one of them said to me, ‘Hey, Grandude.’ … I thought, ‘I kind of like that.’ So from then on I was known as Grandude. So I thought, ‘You know what, it’s actually a nice idea for a book.’ “

Illustrated by Kathryn Durst and scheduled for publication in the U.S. on Sept. 5, 2019, “It’s about a character called Grandude who represents grandfathers everywhere,” McCartney explained, “and he has four grandchildren… and they go on adventures with him. And he’s kind of magical.”

His first children’s book, “High in the Clouds,” with co-authors Geoff Dunbar and Philip Ardagh, was published in 2005.