My first grader read this book to himself.
This is his review-
"I liked it because when he was trying to solve the case, Claude had another case for him to solve. Claude lost his sock. This is a summary of the story: Nate the Great went outside and saw nibbles on his flowers. He looked around and found a tortoise nibbling the flowers. Sludge gave a clue. He was sniffing a lot. Then Nate the Great knew he should follow the trail of the nibbled flowers."
PS He does find Claude's sock!! :-)
-Borrowed from the library.
Guided Reading Level: K (end of 1st grade/beginning of 2nd grade)