The Camp Knock Knock Mystery by Betsy Duffey (9780385323017)

Description - The Camp Knock Knock Mystery by Betsy Duffey

Willie and Crow are back at camp. Last year, Willie won the joke contest and was the knock-knock king. Now Crow wants to get him back. But Willie has a secret weapon--or does he? This time Crow takes charge as Willie must solve the clues hidden in knock-knock jokes to get back his secret weapon--a knock-knock joke book.

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