The Sentry-Box Murder (1935) by Newton Gayle

"Newton Gayle," a pseudonym, was a partnership of strange bedfellows between Muna Lee and Maurice Guinness, a human rights activist and an oil executive, who collaborated on five detective novels about Jim Greer and Robin Underwood – a British detective and his Dr. Watson. Their stint as detective novelists lasted from 1935 to '38 during which they produced a short-lived, colorful series detective novels tied to the regional mysteries of Todd Downing, Elspeth Huxley and Arthur W. Upfield.

Lee was a long-time resident of San Juan, Puerto Rico, who lived there from the early 1920s until her death in 1965 and was married to the man who would become Puerto Rico's first governor, Luis Muñoz Marín. Guinness was a Shell Oil executive stationed in Puerto Rico. So the island was the stage of two of their novels. Murder at 28:10 (1936) takes place during a hurricane and perhaps "the only crime novel to feature a series of barometric charts." The other is The Sentry-Box Murder (1935), alternatively published as Murder in the Haunted Sentry Box, which is also their best-known novel despite being as long out-of-print, little read as the other four titles in the series. Getting listed in Robert Adey's Locked Room Murders (1991) always helps keeping total obscurity at bay.

The Sentry-Box Murder begins on the Calypso, Lord Dampier's ship, which has to make a stopover in Puerto Rico to replenish their fuel supply. Jim Greer and Robin Underwood are on holiday aboard the Calypso, following their "final triumph in solving the O'Donnell Formula mystery," which is where Dick and Cay Piper live – old friends of Underwood. Piper works as an agent for the Canadian-Caribbean company. A job consisting "mostly in herding a lot of tourists round" and "making them happy" ("...requires more tact, diplomacy, and ingenuity than Foreign Service ever did"). Their arrival coincides with Piper having to entertain a VIP party headed by a powerful US senator, John Monarch, who brought along an entourage. Monarch's wife and former actress, Melita Avery, his nephew Elmery Coulton ("...a queer duck") and the lawyer Fergus McKelvie. The party is rounded out by Blaise Grassington, public utilities magnate, and Stella Tophet ("...she's indescribable"). So part of the entertainment for tourists is a treasure hunt at the historic fortress of El Morro with its haunted sentry-box. Piper invites Greer and Underwood to join the treasure hunt, but the outsiders notice Monarch is as powerful a figure as he's unpopular. Suspect "there might develop considerable drama not on Dick's program." They proved to be correct.

During the treasure hunt, Coulton discovers Monarch's body inside the sentry-box with a bullet between his eyes! Shot at close range, indicating the killer was in the sentry-box with him, but two sentries standing guard kept a constant eye on the box and only saw Monarch go inside. And no gun found inside the box! So how did the killer manage to shoot him when nobody could have gone in, or out, without being seen by the guards?

This naturally all smacks of John Dickson Carr or Hake Talbot. A brief history tells of two haunted sentry-boxes on the island "supposed to be the special domain of the Devil." One of the boxes, one at San Cristóbal, makes people vanish without a trace, while this one at El Morro kills people. So basically a classic room-that-kills and it's mentioned Monarch, an Irish-American, has a banshee in the family. However, the supernatural frills are just that, frills and background decoration. Nothing is done with it. So to present it as anything even remotely Carr-like or an ancestor of Talbot would be misleading. If the writing duo of Lee and Guinness modeled their work on anyone, it probably was Sir Arthur Conan Doyle and the American mystery writers of the day such as S.S. van Dine and Ellery Queen.

Jim Greer and his narrator, Underwood, give the story a Sherlock Holmes and Dr. Watson vibe, but that's because Underwood is more like a Dr. Watson than Greer is a Sherlock Holmes. Greer simply is another attempt to imitate, improve and maybe try to humanize the Philo Vance type of detective character – which was done here with various degree of success. Greer is certainly a fun enough detective, sneaking and sleuthing in the background, obsessing over nebulous clues and minor matters. Like a packet of soiled shirts left in the bushes, scribbles on a cuff, whispered threats of revenge and fretting over the disharmonious array of motives ("where's revenge!"). Like I said, a fun enough character who fulfills his duties as Great Detective, but ultimately a fairly paint-by-numbers detective character. You can honestly say that about most of the characters and plot. Funnily enough, that's where the book's greatest strength shines the brightest.

I think the greatest accomplishment here is how the authors trotted out a cartload of old, recycled ideas, tropes and cliches and somehow made it feel like a fresh treatment. Not just because of its colorful backdrop by staging a murder during a treasure hunt in "an old Spanish castle on a tropical island." For example, the solution to the impossible shooting of Monarch in the sentry-box dates back to (SPOILER/ROT13) Qblyr'f fubeg fgbel “Gur Ceboyrz bs Gube Oevqtr” (oryvrir vg jnf hfrq va n Cuvyb Inapr abiry) and has been used way too often as a cheap, rage-inducing cop out explanation for various impossible crime stories with vgf fhvpvqr-qvfthvfrq-zheqre tbgpun. But here it was used to disguise a murder as an impossible murder. Yeah, that part falls a little flat without playing up the supernatural part, but liked how it was integrated with the treasure hunt and appreciated it tried to do something good with an otherwise terrible idea. That and not getting another fhvpvqr-qvfthvfrq-nf-zheqre fbyhgvba. Another thing done very well was how Greer worked towards a neatly posed false-solution, but, as to be expected, the correct solution underwhelms. Worse even, it betrays the authors hadn't played quite as fear with their readers as the list of clues would suggest.

That there's always a "but" is what keeps Gayle's The Sentry-Box Murder from a place in the first-ranks of 1930s mystery novels, but, to give it a positive bend, it's a solid second-stringer. Remember a second-stringer is not the same as a second-rate mystery. The Sentry-Box Murder is not second-rate, but misses the rigor and finesse of a truly first-rate mystery. Just a solid second-stringer that some probably wish had been more like Carr or Talbot. If you want an alternative take, Pietro De Palma, of Death Can Read, reviewed The Sentry-Box Murder in 2022 and called it a "beautiful novel from the golden age of mystery!"

Notes for the curious: to be fair to Lee and Guinness, they appear to have improved from book to book. Their first, Death Follows a Formula, also seems to be their worst with the detection being drowned out by lectures on oil manufacturing and economics. So, if that's true, The Sentry-Box Murder stands as a marvelous improvement. Martin Edwards reviewed Murder at 28:10, praising the building of tension and its sound plot, but thought the characterization was flimsily. Edwards also reviewed Sinister Crag (1938), "appealing and atmospheric," which is the last in the series. Death in the Glass (1937) has not been reviewed recently, but contemporary reviews appear to have been mixed. One calling the book a smooth, well done, but average, mystery and the other it had to odor of "desperate originality" about it. So maybe they relapsed in that one, but their partnership seemed to have ended when they started to get it down. I suppose Guinness was called away from Puerto Rico, because he returned decades later with three solo-thrillers, Man in Danger (1961), Man on the Run (1962) and Man Against Fear (1966), published as by "Mike Brewer."