Minerva Clark goes to the dogs by Karen Karbo is a book my daughter read last summer. She said it was a good mystery book. I copied the description below.
"Minerva Clark has never liked popular, bratty Chelsea de Guzman. But when Chelsea pleads with Minerva to help her locate a missing diamond, the prospect of a new mystery is just too irresistible to pass up, especially after Minerva learns that it's a red diamond and potentially worth millions. Before long Minerva is doing what she does best: getting into trouble while getting to the bottom of things. And whether that includes digging through a day's worth of trash, tangling with some crooked animal shelter workers, dodging three mischievous corgis, or tracking a carrier pigeon with intestinal problems, Minerva is determined to get her man--or his best friend…"