https://www.penguinrandomhouse.com/books/690086/theres-a-unicorn-in-your-book-by-tom-fletcher-illustrated-by-greg-abbott/
There's a Unicorn in Your Book by Tom Fletcher: 9780593434765 | PenguinRandomHouse.com: Books
Galloping glitter! A unicorn has landed in YOUR book! An engaging new adventure from the team that brought you There's a Monster in Your Book and...