Series numeration from goodreads.com

Sequel to: There's a murder afoot.

After Gemma helps a little girl find her lost cat, the child returns seeking further assistance when her mother is accused of killing her garden club rival.

Young Lauren Tierney comes to the Sherlock Holmes Bookshop and Emporium to beg Gemma to find her missing cat, Snowball. Gemma's dog Violet follows her nose to a neighbor's garden shed, and Gemma basks in praise for a job well done. A few days later Lauren is back for a far bigger job: Her mother has been accused of murdering her garden club rival. Sheila Tierney's garden had been vandalized the night before the West London Garden Club's early summer tour. Sheila confronted Anna Wentworth in a towering rage, and after Anna won the trophy for best garden she was found murdered. Now Sheila Tierney is the prime suspect. -- adapted from jacket