Maurice Sendak, the late author and illustrator of Where the Wild Things Are, has left behind an unpublished book that’s set to be published in the fall of 2018 by HarperCollins.

Presto and Zesto in Limboland was created by Sendak and lifelong friend Arthur Yorinks, who announced the book’s release last week.

“Nearly twenty years ago, Maurice and I, inspired by our friendship, conceived this book about two friends making their way in a very mixed-up world,” said Yorinks.

“Publishing Presto and Zesto in Limboland with the help of our editor, Michael di Capua, and Lynn Caponera, is not only a stroke of serendipity. It is a moment of sublime joy.”

According to The Guardian, the book was found by Lynn Caponera — manager of the Sendak estate and President of The Maurice Sendak Foundation — in his Ridgefield residence.

“What a miracle it was to find this treasure buried in the archive! It’s just as fresh and appealing as when Arthur and Maurice created it. It’s an unexpected gift for all of us,” said di Capua.

“The wonderful thing about this Foundation is that its board is made up of friends who loved and worked with Maurice. We can all still hear him whispering in our ears, guiding us on how to care for his legacy,” said Caponera.

Best known for his groundbreaking Where the Wild Things Are, Sendak’s illustrious career spanned more than 60 years, establishing him as one of the most consistently inventive and challenging voices in children’s literature.

With other illustrators, Yorinks has published 36 children’s books, including HEY, AL, a Caldecott Medal winner.

Over their 40-year friendship, Yorinks and Sendak also collaborated on The Night Kitchen Theater and the dance piece "A Selection."