"I am not a consulting detective," Gemma Doyle reluctantly tells 10-year-old Lauren Tierney, when the little girl comes to the Sherlock Holmes Bookshop and Emporium to beg Gemma to find her missing cat, Snowball. Gemma might not be able to follow the clues to find the cat, but her dog Violet follows her nose to locate the missing kitten in a neighbor's garden shed. Gemma and Violet proudly return Snowball to her grateful owner, and Gemma basks in praise for a job well done. But a few days later Lauren is back with ten dollars in hand, wanting to once again hire a consulting detective, and this time for a far bigger job: Her mother has been accused of murdering her garden club rival.
