Halloween Bingo - Locked Room Mystery

In a fun turn of events, in need to change my plans for the Locked Room Mystery square: I originally planned to read The Tokyo Zodiac Murders for this square, but we just started another Holmes buddy read - The Sign of Four, which also features a locked room mystery.
I'm sure I will still read The Tokyo Zodiac Murders at some point, but I'll use The Sign of Four for the square.