Walker & Co. continues its laudable reprintings of the long-out-of-print works of the late English-mystery master, whose witty cases all feature Gervase Fen, a most un-donnish Oxford prof of English literature. This 1945 outing, written when Crispin (real name--Robert Bruce Montgomery) was 24, and published in the U.S. by Lippincott in 1946, involves the murder of a cathedral organist. (Montgomery's other career, which partly explains the 20-year-gap between Beware of the Trains and Glimpses of the Moon, was as composer and organist.) Not perhaps the very best of Crispin--that will come later with the less fluttery Love Lies Bleeding and The Long Divorce--but an absolute must for devotees of cultivated crime fiction drenched in literary/musical/historical associations.