Nate the Great and the Missing Key by Marjorie Weinman Sharmat illustrated by Marc Simont*

My first grader read this book to himself.
Annie is trying to set up a birthday party for her dog Fang.  She, however, loses her house key and cannot enter the house to prepare for the party.  Can Nate find the key before Fang's party is to start?
*Highly recommended by my first grader.
-Borrowed from the library.
Grade Level Equivalent: 2.9