ISBN-13: 9780142422250 / Angielski / Miękka / 2015 / 32 str.
Cam, her best friend Eric, and Eric's mom are spending the day with Eric's grandparents. But Grandpa and Grandma seem too tired to visit. Every so often, a knock at the door wakes them up. But when they go to answer, no one is there. Is a Knock, Knock Ghost on the loose? It's up to Cam to solve the mystery
Garden State Children's Book Award 2017 Nominee.