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A century after it was written, an unpublished Beatrix Potter story, The Tale of Kitty-in-Boots, will finally make its way into readers’ hands. The tale was discovered two years ago by Jo Hanks, publisher at Penguin Random House in the U.K., while she was perusing an out-of-print literary history of Beatrix Potter. In a letter to her publisher, Potter described the then-unedited manuscript as the story of “a well-behaved prime black Kitty cat, who leads a double life.” According to letters found in the Potter archive, the author never finished the tale because “interruptions began” — interruptions like World War I and sheep farming.

Three handwritten manuscripts were found in the V&A archive, according to the publisher, as well as a rough color sketch of Kitty-in-Boots, a dummy book featuring some of the manuscript set in type, and a pencil sketch of Mr. Tod, the story’s arch-villain.

“The tale really is the best of Beatrix Potter,” said Hanks in a release. “It has double identities, colourful villains, and a number of favourite characters fom other tales (including Mr. Tod, Mrs. Tiggy-Winkle, Ribby, and Tabitha Twitchit). And, most excitingly, our treasured, mischievous Peter Rabbit makes an appearance — albeit older, slower, and portlier.”

As if this discovery weren’t exciting enough, Quentin Blake — best known for his creepy, iconic illustrations for Roald Dahl’s books — will be illustrating the tale. “It seemed almost incredible when, early in 2015, I was sent the manuscript of a story by Beatrix Potter; one which had lain unpublished for a hundred years and which, with the exception of a single drawing, she had never illustrated,” Blake said in a release. “I liked the story immediately – it’s full of incident and mischief and character – and I was fascinated to think that I was being asked to draw pictures for it. I have a strange feeling that it might have been waiting for me.”

The Tale of Kitty-in-Boots will be published on September 6 in honor of Potter’s 150th birthday.