This is book number 1 in the The Critter Club series.
“During spring break, Amy is worried about being lonely because all her friends have big plans, and all she is going to do is help her mother at the veterinary clinic and read her new Nancy Drew mystery. Things get exciting fast, however, when Mrs. Sullivan, the intimidating rich lady who lives in the mansion at the end of town, brings her puppy, Rufus, into the clinic and then comes back later that night in tears because Rufus has run away. Suddenly, Amy has a real mystery to solve! Big print, great illustrations, and a story that is clear and easy to follow make this a very good chapter book for young readers.”
— Julie A. Baker, Eight Cousins, Falmouth, MA