All At Sea Transcript

Caroline: When constructing a plot for a detective novel, nothing matters more than boundaries. It’s vital to know where the edges of the world will be, and who will be allowed to come in and out once the mystery is in progress. After all, it’s no fun at all if basically anybody within a hundred mile radius of the corpse is a suspect.

Some of the most memorable and famous murder mysteries are the ones where the writer allows a distinctive location to do this — think of Agatha Christie’s And Then There Were None, with the characters marooned on a small island off the coast of Devon. Certain institutions and buildings can work as isolating or limiting devices too, and I’ve covered a few of them in past episodes, such as schools, snowed in country houses and trains.

Part of what makes the island setting work so well, though, is the absolute finality of it. Unlike with a train carriage, say, where there’s always the possibility that a murderer is going to improbably swing down from the roof, it’s completely plausible to the reader that nobody can cross a turbulent sea. But even Agatha Christie, who wasn’t above repeating a plot every now and then, couldn’t keep sending characters to die on remote islands. Luckily, there’s a much more commonplace and believable version of this that works just as well.

What could be better place for a murder than a boat, all at sea?


Welcome to Shedunnit. I’m Caroline Crampton. This episode has a distinctly nautical flavour, and before we get into it properly, I want to explain why this subject interests me so much. I grew up spending an awful lot of time on boats, you see, and sailing is the reason my family is even in Britain. In the early 1980s, my South African parents built their own boat from scratch and sailed it up the Atlantic, eventually settling on the Isle of Sheppey in the Thames estuary, which is where I was then born and grew up. Although nobody was ever murdered onboard, thank goodness, long weekends spent sailing across the North Sea as a child and then a teenager gave me a very healthy respect for the sea and a reasonable grasp of seamanship. I did a lot of reading by the light of an oil lamp swinging from the cabin ceiling while we were anchored, with the waves lapping against the hull and someone else turning the pages of their book the only sounds to be heard.

I wrote a whole book myself about this odd childhood I had sailing on the Thames estuary, which is called The Way to the Sea comes out in paperback on 5 March. There’s lots in there about sailing and belonging, and I also snuck a reference to Harriet Vane into the first chapter, just in case Shedunnit listeners needed an extra reason to check it out. There are links to places where you can buy it at You can just search The Way to the Sea at your book retailer of choice, or ask a bookseller in your local shop to order it for you.


With my credentials on this topic established, let’s have a look at the primary way in which detective novelists have used boats in their murder mystery stories. I already alluded to this at the start, but let’s be clear: a boat, especially one that’s far out to sea, is a brilliant way of creating that closed circle of suspects that is really a requirement for crafting a classic whodunnit. Although lots of writers in the heyday of this form in the 1920s and 1930s did enjoy bending or even breaking many of the so-called rules of the form, that one that was respected most of the time had to do with introducing the murderer early on. “The criminal must be someone mentioned in the early part of the story,” as Ronald Knox put it in item one of his famous “decalogue” from 1928. And for this to work without immediately giving away the murderer’s identity, it’s best if murderer, victim and suspects are all part of a temporarily closed group. That way, the reader can get to know a finite number of characters quickly, and it also cuts off the possibility that the real culprit might be someone unconnected who wandered in off the street, did the deed, and the disappeared without trace. Because where’s the fun in that?

A group travelling on a boat is a perfect closed circle, then. During the interwar years when popularity of this kind of classic crime novel was at its height, commercial air travel only just beginning to become popular and accessible to the masses. Especially for intercontinental journeys, ocean liner was still the obvious way to travel. For the detective novelist, this setting is perfect. The sea keeps suspects tightly contained, while the anonymous nature of travel means that all sorts of strangers can be plausibly collected together.

One of the foremost examples of this effect in action can be found in Singing in the Shrouds by Ngaio Marsh. It’s one of her later books, published in 1959, and the twentieth to feature her regular Scotland Yard sleuth Roderick Allen. As the title would suggest, the action takes place on board a ship — the Cape Farewell, departing from London for the voyage south down the Atlantic to Cape Town. Marsh chose her vessel carefully: the Cape Farewell is a cargo ship and doesn’t take many passengers, meaning that aside from the captain and crew, there are only nine people on the ship for the reader to become familiar with.

The setup is dramatic, too. The ship is about to depart from the Pool of London on a foggy night when the body of a strangled woman is discovered on the deck. From various trophies scattered about, it is deduced that this woman is a victim of the so called “Flower Killer”, a serial killer currently terrorising the city. She’s also still holding part of a ticket for the Cape Farewell’s voyage, so it’s assumed that the murderer must be one of the passengers on the ship. Alleyn is able to join the ship before it reaches the Atlantic, and what follows is an extremely enjoyable, if somewhat claustrophobic, shipboard murder mystery. It’s no surprise that Marsh handles this setting deftly. She lived most of the time in her native New Zealand, but made regular trips to the UK and America, always preferring to travel by cargo ship when she could because of how much more peaceful it made her voyages compared to the big commercial liners. She might not have encountered a serial killer, but she certainly knew first hand about the routines and layout of such ships, and had observed for herself what kind of people liked to travel on them.

Another novel with a not dissimilar premise is Nine – And Death Makes Ten by Carter Dickson. This book was published in 1940, and can also sometimes be found under the titles Murder In The Submarine Zone or Murder in the Atlantic. Carter Dickson is a pseudonym of the American golden age author John Dickson Carr, and this was one of the many books he wrote featuring his series detective Sir Henry Merrivale. As Marsh would a couple of decades later, Dickson Carr chose to set his story on a particular kind of ship that helped to keep the cast list very small. The book is set during the Second World War and the S.S. Edwardic is mostly being used as a munitions transport across the Atlantic, although there are also nine passengers on board. As one of the alternate titles underlines, the ship is under constant threat from U boat attacks. It’s travelling in a blackout, and Dickson Carr does a great job of amping up the fear and foreboding out there in the Atlantic in 1940. Of course it then turns out that there is danger onboard too, when a woman is found with her throat cut. The murderer has left two nicely clear fingerprints at the scene of the crime, though, except investigation then shows that they don’t match anybody on board. If there aren’t any stowaways, and it’s not any of the passengers or crew, who killed her? A wonderful setup, and it’s only enhanced by the restrictions of its maritime setting.

Of course, Marsh and Dickson Carr were far from the only writers to position their closed circle of suspects on board ship, but I do think these two novels are among the finest of the form. We might also include The Man in the Brown Suit by Agatha Christie, too, although the sea voyage is only one section of a more convoluted journey in that book. An honourable mention goes to the often overlooked writer Christopher St John Sprigg, who in 1935 published a short story titled “Four Friends and Death” that I think is an outstanding closed circle maritime mystery. The four friends of the title are just sitting down to a meal in the cabin of a yacht at anchor, celebrating the fact that they have successfully come through a nasty crossing of the Bay of Biscay. They’ve just reached the after dinner brandy stage when one of the four falls face down on the table — poisoned by Prussic acid. The remaining three then have to confront the fact that one of them is a coldblooded, highly opportunistic murderer, because nobody else could possibly have come on board and slipped the poison into the glass. It’s an extremely clever and twisty short story, and reading it only makes me sorry that Sprigg didn’t live to write more crime fiction — he was killed at the age of 30 while fighting for the British Battalion of the International Brigade in the Spanish Civil War.

After the break: what happens out at sea, stays out at sea. Or does it?

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An important way in which boat based mysteries differ from those set on other forms of transport, such as trains, is that the boat itself can serve both as the setting and the means of murder. Regular listeners will know that I did a whole episode last year about trains in detective fiction, and I don’t think I talked about many stories where the dastardly plan of the villain was to drive a train over someone, in that silent film “woman tied to the tracks” way. However, there are plenty of times when a boat is intrinsic to the way someone is killed. Edmund Crispin ably demonstrates this in a short story from his Fen Country collection called “Man Overboard”. In that tale, a pair of American crooks who are in hiding in Britain take to sailing as part of a life insurance scam, which then has surprising and fatal results. Agatha Christie works this line too in a story from the early Miss Marple collection The Thirteen Problems. In “The Blood Stained Pavement”, murderers and victim are repeatedly confined in a small rowing boat on a supposedly jolly outing, from which the crime can be committed and disguised out of sight. This is the point, you see — nobody about from others on board can see what you’re doing on a boat far out to sea, and being afloat on water removes the potential for a lot of the clues that detectives usually rely on. There can be no footprints, disturbed undergrowth, flattened grass, or any of the other tell tale signs of nefarious activity on land that golden age sleuths know to look out for. Boat based murder mysteries represent a challenge to detectives and writers, then, which might explain why there are more examples in the short story form than there are full length novels. The shorter mystery requires less detailed explanation.

Another key consequence of setting a murder mystery on a boat is the opportunities it offers for the easy disposal of evidence. Police in detective fiction seem to have extraordinary luck when it comes to finding murder weapons in bushes and stuffed into the backs of wardrobes, but their job is made that much harder when there’s a handy river or sea into which someone can drop a revolver. There’s a pre golden age example of this in a short story from 1897 by LT Meade and Robert Eustace called “The Eight Mile Lock”, in which a diamond necklace is stolen during a party on a houseboat anchored on the Thames. The water all around prevents a getaway or a handoff, so the stolen goods must either be still in the boat, or in the water.

Agatha Christie’s Death on the Nile makes good use of the water too, with an incriminating pistol and wrapper thrown overboard from the Egyptian steamer where Hercule Poirot and his fellow tourist passengers suddenly find themselves in the midst of a murder plot. The circle of suspects isn’t quite as neatly closed in this book as in Singing in the Shrouds, say, just because of the boat being on a river it is passingly plausible that someone from outside could come on board unseen during a stop. However, Christie does take advantage of the physical setup of a Nile steamer, allowing witnesses to overhear crucial moments from cabins positioned next to each other, or out on the communal deck. And of course, the fact that the characters must eat and relax together in communal areas is a great help to a novelist trying to establish relationships for the reader.


I mentioned John Dickson Carr earlier in this episode, and I want to circle back to him now because of his stellar reputation in one particular subgenre of detective story: the locked room mystery. Actually, the novel I talked about, Nine – And Death Makes Ten, isn’t a classic locked room story, but rather an “impossible fingerprint” one, but most of the rest of Carr’s output under his Carter Dickson pseudonym does fall into this category. Locked room mysteries or impossible crimes, for those not familiar with the terms, are pretty much what you might assume from the names — a corpse is usually found inside a locked room or space with no apparent way of a murderer getting inside and then out again to do the deed. Carr was a master at adding extra details to make his setups that much more impossible, such as in The Plague Court Murders when the body is discovered inside a locked cottage that has 30 feet of undisturbed mud around it, apparently showing that nobody even approached the building, let alone went inside.

Boat based mysteries can offer a similar guarantee for locked room stories. I really like one called Bullion! from 1911 by an author called William Hope Hodgson. In it, a ship is transporting gold bullion from Australia to London when the captain begins to fear that there are ghosts on the ship. Investigation of the sealed room where the gold is being kept reveals that some funny business is going on, with whisperings in the air and chests disappearing and reappearing in the middle of the night. A round the clock watch is established until they reach port, and there is seemingly no way in which thieves could get at the loot. And yet, when they inspect the chests… I’ll let you read it for yourself to find out exactly what happens, but it’s a great example of a locked room mystery enhanced by being set at sea, when the water itself provides an added level of difficulty to the puzzle.

Hodgson was a lifelong professional sailor, having run away to sea at the age of 13, and his first hand experience certainly helps to make his story more vivid and believable. This is generally the case with maritime mysteries, I find — when the writer has some personal knowledge of sea travel, either as a regular passenger like Ngaio Marsh or as a sailor like Hodgson, there tends to be more realistic detail.

I do especially enjoy stories where it is little details about sailing that hold the key to the plot, such as in Josephine Bell’s “The Thimble River Mystery” from 1950. It concerns the death of an amateur yachtsman while his boat is on its mooring in a small river off Southampton Water. She includes lots of small nautical details like the state of the tide, the use of fenders and the way a halyard is tied as a way of building up the plot, and as someone who grew up being drilled in the correct way to use a cleat and the right knots for fenders, it’s very gratifying to see this stuff serving a purpose in detective fiction. I should also mention The Floating Admiral here, which I talked about way back on episode 12 of this podcast. The maritime details aren’t quite so sharp in this book, because it’s a collaborative, round robin work written together by 12 members of the Detection Club. But as the title suggests, the murdered man has been a senior Naval officer, and his discovery as a corpse floating in a rowing boat on a tidal river gives some of the writers great scope to use tides and ropes to create and break alibis.

Of course, not all boats in detective fiction serve such a clear purpose in the plot. It would be remiss of me to end this episode without mentioning the Freeman Wills Crofts novel Fatal Venture, the first half of which is almost entirely taken up by a speculative scheme to launch a cruise ship line to circle Britain’s coast. It’s not really a spoiler to say that this actually has nothing really to do with the crime Inspector French eventually investigates — Crofts just really liked boats and found it interesting to write about one.

But most of the time when a detective story is set on a boat, you can be fairly sure of getting a twisty, smart plot that makes good use of the boundaries and restrictions imposed by its setting. After all, to most of us, the sea itself is a mystery.


This episode of Shedunnit was written, narrated, and produced by me, Caroline Crampton. You can find show notes at where there will also be links to order my book. I provide transcripts for every episode of the podcast too: find them at

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I’ll be back on 18 March with another episode.

Next time on Shedunnit: Prejudices.

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