Walking her dog late one night, Gemma Doyle, owner of the Sherlock Holmes Bookshop, smells smoke outside the West London Museum. No one is inside, but the museum's priceless collection is ruined. Baker Street's shop owners come together to hold an afternoon auction tea to raise funds to rebuild. But the auction never happens. Before the gavel can fall, museum board chair Kathy Lamb is found dead in the back room. Now Gemma will have to use her deductive prowess to find the killer - before her fellow shopkeeper Maureen is arrested for the crime.