Sherlock Holmes and Dr. Watson are called in to investigate a politically sensitive case involving the death of a local Anglican priest who is hosting a secret international meeting of religious leaders. Among the guests is a quiet unassuming priest, serving as an interpreter for one of the foreign guests, Father Brown. Holmes races against the clock to solve this murder before the word spreads to the visiting priests consulates and a murder becomes an international incident. He is assisted as always by Watson and an occasional well-timed question or comment by Father Brown.
Hercule Poirot is the featured detective in this book though he is barely mentioned in the first half of the novel. Events are seen through the eyes of two other characters and then Poirot is asked to investigate the death of a tyrannical matriarch at Petra. Was it murder or was the journey to beautiful Petra just to much for her?