Triangle (The Shapes Trilogy)

Part of the Shapes Trilogy, the books that inspired Shape Island from Apple TV+

Multi-award-winning, New York Times best-selling duo Mac Barnett and Jon Klassen conspire again on a slyly funny tale about some very sneaky shapes.

Meet Triangle. He is going to play a sneaky trick on his friend, Square. Or so Triangle thinks. . . . With this first tale in a new trilogy, partners in crime Mac Barnett and Jon Klassen will have readers wondering just who they can trust in a richly imagined world of shapes. Visually stunning and full of wry humor, here is a perfectly paced treat that could come only from the minds of two of today’s most irreverent — and talented — picture book creators.

Mac Barnett, the 2025–2026 National Ambassador for Young People’s Literature, is a New York Times best-selling author of stories for children. His work has been translated into more than thirty languages and sold more than five million copies worldwide. Mac Barnett’s books have won many prizes, including two Caldecott Honors, three New York Times/ New York Public Library Best Illustrated Children’s Book Awards, three E. B. White Read-Aloud Awards, the Boston Globe–Horn Book Award, Germany’s Jugendliteraturpreis, China’s Chen Bochui International Children’s Literature Award, the Netherlands’ Zilveren Griffel, and Italy’s Premio Orbil. He is the cocreator, with Jon Klassen, of the Substack Looking at Picture Books, as well as Shape Island, a stop-motion animated series on Apple TV+, based on their best-selling Shapes series of picture books. Mac Barnett lives in Oakland, California.

Jon Klassen is the creator of the #1 New York Times bestselling I Want My Hat Back, which received a Theodor Seuss Geisel Honor, and its companions, This Is Not My Hat, which won a Caldecott Medal and a Kate Greenaway Medal, and We Found a Hat, named a Publishers Weekly Best Children’s Book of the Year. He is also the creator of the Your Places and Your Things board book series, as well as the picture books The Rock from the Sky and The Skull. He is the illustrator of How Does Santa Go Down the Chimney?, Extra Yarn, Sam and Dave Dig a Hole, and the Shapes Trilogy, all by Mac Barnett. For his contributions to children’s literature, Jon Klassen is a member of the Order of Canada and was named the 2026 recipient of the Astrid Lindgren Memorial Award. Originally from Niagara Falls, Ontario, Jon Klassen now lives in Los Angeles.