The show is coming to town on Cape Cod. The West London Theater Festival is putting on a stage production of The Hound of the Baskervilles. Gemma Doyle is excited and participating with her friend Jayne Wilson, whose mother, Leslie, just happens to be volunteering with the company. Leslie arranges a fundraising tea party at the home of the festival organizer, catered by Mrs. Hudson’s Tea Room. The tea is a rousing success, but Sir Nigel Bellingham, the famous star cast as the lead of Sherlock, goes missing. And Gemma finds him at the bottom of the cliff. Dead.

Before the tea, Sir Nigel had come by the Sherlock Holmes Bookshop, only for Gemma to realize that he’s not at all suited to the role. But as Gemma and Jayne investigate, the list of suspects just grows longer. Long past his prime, Sir Nigel was second to a younger actor who had first been given the role. The festival’s executive director also expressed that he had been hired over her objections. Then there are the slew of people to whom Sir Nigel was rude. They all have motive, but then a scrap of Leslie’s apron caught on a bush by Sir Nigel’s body is found. And the police are set to pounce as she becomes suspect #1.

It’s up to Gemma and Jayne to team up again and clear Jayne’s mother’s name in The Cat of the Baskervilles, the delightful third Sherlock Holmes Bookshop mystery.