Wealthy philanthropist and prominent Sherlockian David Masterson has rented Suffolk Gardens House, where he plans to entertain his friends in a traditional English country house weekend. As the chosen caterers, Jayne Wilson and Gemma Doyle get to work preparing lavish meals and setting up Sherlockian props for entertainment. It quickly becomes apparent that David's guests don't like each other—or their host. In this 7th case (after A Curious Incident), a poisoned dart sails through the window of the library, presenting Gemma Doyle with a unique problem.