After a dinner commemorating the end of the Great War, Penny Brannigan and her guests adjourn to the library to view the Black Chair, a precious piece of Welsh literary history, only to see that it is missing, and the dead body of a waiter is nearby. When Penny learns that the victim was the nephew of one of her employees, she is determined to find the killer, but meanwhile the Prince of Wales is due to open an exhibit featuring the chair in three weeks. Following The Marmalade Murders, Penny's tenth case will force her to consult an ex-thief, a disagreeable antiquarian, and an eccentric herbalist, but in this double investigation, time is not on her side.