Like a Thief in the Night: "The Diamond Pentacle" (1939) by Carter Dickson

John Dickson Carr's "The Diamond Pentacle," published as by "Carter Dickson," originally appeared in The Times on November 15, 1939, but reprinted only once in Merrivale, March and Murder (1991) – a now out-of-print collection with a three-digit prize tag for used copies. So, consequently, "The Diamond Pentacle" ended up as one of Carr's least-known, most obscure short stories. Even more so after The Island of Coffins and Other Mysteries from the Casebook of Cabin B-13 (2021) gathered Carr's extremely obscure Dr. John Fabian series.

Only two people have reviewed "The Diamond Pentacle" over the years and they praised it. Pietro de Palma, of Death Can Read, opened his review calling it "among Carr's best short stories ever," while Christian Henriksson of Mysteries, Short and Sweet liked the solution to the locked room "because Carr bamboozles us all with a twist that is superb in all its simplicity." Let's find out!

Carr's "The Diamond Pentacle" takes place during a lazy, midsummer getaway at Broadlawns where Sheila Lake is spending a fortnight with her fiancé, Dick Mason – chaperoned by Major and Mrs. Prentice. They are friends of Sheila's uncle and aunt, Bartholomew and Martha Lake, currently away on business. They're at the very least suspicious, because Dick has been tight lipped and secretive about his occupation and wealth ("...your Aunt Martha rather prefers the measles to me"). And it doesn't help he has a penchant for some wild ideas ("like that scheme of yours for robbing the Bank of England"). Story's opening finds him reading the biography of an escape artist, named Mephisto, who "had wormed his way out of locked rooms, locked safes, Russian prison-vans and roped chests at the bottom of a river." That leads to a discussion and a bet.

Sheila is sleeping in the bedroom of her uncle and aunt, which has the properties of a burglarproof safe. The bedroom windows are covered with solid, narrow iron grills and a nearly two inch thick door with "a bolt like a bank vault." Not without reason. The bedroom has a small wall-safe, protected with a letter-lock combination, storing the titular pentacle. Dick tells Sheila he can probably sneak into her bedroom at night, while the room is securely locked and bolted ("I won't touch the safe"). Somehow, Dick manages to take Sheila's wristwatch from her bedside stand and replaces it with his own. But the second time, Dick has gotten hold of the pentacle. But why? And how! This two night miracle is followed by the arrival of a letter from a private investigation firm and the return of Sheila's aunt and uncle. Yes, the solution places a great spin on what appeared to be the case.

Now, simply as a short detective story and locked room mystery, "The Diamond Pentacle" is fairly minor stuff coming from a writer like Carr, but therefore not any less entertaining. And, yes, the final twist is great in all its simplicity. What it perhaps lacked was an additional ten pages and a floor plan of the bedroom to push my opinion closer to that of Pietro. But as it stands, I very much enjoyed "The Diamond Pentacle" and even more enjoyed reading a "brand new" Carr. It makes me want to finally pick up one of those last remaining unread Carr novels like The Nine Wrong Answers (1952), Scandal at High Chimneys (1959) or Deadly Hall (1971).