If you like Golden Age locked room mysteries this is a good one! Deep Lake Mystery (1928) by Carolyn Wells, author of The Clue, is set in the lake region of Wisconsin. Our narrator Gray Norris is invited to join his old friend, the detective Keeley Moore, and his new wife at their vacation cottage at Deep Lake, Wisconsin for a relaxing month of fishing, swimming, boating, and just getting away from the hustle and bustle of the East Coast. That goes by the wayside when one of the Moores neighbors, a millionaire Sampson Tracy, is found murdered in a locked room with a nail driven into his skull and his corpse festooned with bizarre ritualistic items, and other seemingly meaningless articles. Find the motive and you find the criminal!