Mycroft's precious rhetoric to prove a presumable suicide is murder. Mr. M., accompanied by argumentative Silchester, in renting a house, displays his knowledge of the finer points of history, literature, art and human nature, while tracing the killer. A twin house, a spring, an old, old hair-pin, a passage in the classics, and the unrelenting observance of a neighbor add up to the concealing of a crime. Sedentary cerebration.