It is far from his best work but, in his final novel, Sir Arthur Conan Doyle delivers a short and agreeable piece of routine adventure fiction. The Maracot Deep is, for the most part, a sea-adventure in the tradition of Jules Verne: three men, led by the brilliant professor Maracot, are descending into the depths of an ocean abyss – the titular Maracot Deep, named after its primary explorer – in a diving bell. After their lifeline is severed by a sea monster, they plunge deeper and deeper, beyond hope of rescue.

At the sea bottom, they discover the lost city of Atlantis, beginning the novel's second act. As lost cities go, I found this one a bit underwhelming. The Maracot Deep failed to truly bring out the wonder of this iconic legend, which has fascinated us ever since "Plato's report of Egyptian gossip" (pg. 42). Doyle's telling is conventional – Atlantis was an advanced civilisation, a 'missing link' which had "thrown out one arm to Central America and one to Egypt, and so left traces of themselves" (pg. 63) before collapsing into volcanic apocalypse and the tumult of the waves. By the time Maracot and his companions – Headley, who narrates the story, and Scanlan – encounter it, it is a diminished outpost of a few thousand people. To make the bit work, Doyle hand-waves away the scientific problems of water pressure at such crushing depths (in short, our established science is shown to be wrong), the darkness (Doyle's ocean floor is bioluminescent), and of oxygen (the Atlanteans have an advanced technology which is effectively an oxygen bubble worn around the head).

It's fine pulp-adventure fare, but no more than that. Nothing much is done with Doyle's Atlantis and its community never impresses itself upon the reader. Development of both plot and world-building is nil, and the sub-plot of Headley's love-interest, an Atlantean girl named Mona, is so sparse that I don't know why Doyle even bothered. Even by the standards of such gentleman-adventures, where women and romance are inconvenient distractions to all the manly exploration and camaraderie, The Maracot Deep felt shallow here.

Nevertheless, the novel sprung a strange surprise in its third and final act. Indulging Doyle's mysticism and spiritualism, which emerged towards the end of his life, the narrator Headley relates the three explorers' encounter with an ancient demon, once worshipped by some castes of Atlantis. Taking in ideas of reincarnation, a spiritual battle between good and evil, and outright magic, it was an abrupt shift in tone from the (broadly speaking) analytical and science-based fiction of the preceding acts.

The confrontation with this Ba'al-like demon reads like an abridged Tolkien, anticipating Gandalf's battle with the Balrog in The Lord of the Rings ("Go down into the Hell that has been waiting for you so long," Doyle has one of his characters incant on pages 147-8. "You are a prince of darkness. Go where the darkness is.") Even more peculiar was the demon's introductory boast on page 139, which had me wondering if Mikhail Bulgakov, who started writing The Master and Margarita in the year Doyle published The Maracot Deep, had ever come across some edition of it. "I am the master of the mob," Doyle's debonair devil says. "Where evil has been planned there have I ever been. I was with the Huns when they laid half Europe in ruins. I was with the Saracens when under the name of religion they put to the sword all who gainsayed them. I was out on Bartholomew's night. I lay behind the slave trade. It was my whisper which burned ten thousand old crones whom the fools called witches. I was the tall dark man who led the mob in Paris when the streets swam in blood. Rare times those, but they have been even better of late in Russia."

Many will find this end to the story more than a little bit kooky, but I quite liked Doyle's muddying of the waters here. It at least brought a bit of froth to what was threatening to become stale. Arthur Conan Doyle's final novel is for the most part hasty and conventional, but its emergent oddness meant "in some ways I wish that we could have stayed longer in the Maracot Deep for there were many mysteries there…" (pg. 110) ( )

Professor Maracot with a sturdy sailor and a young student (the narrator) are exploring the bottom of the Atlantic in a superior diving bell when they are cut off by a storm which sinks their mothership. They are rescued by the descendents of the inhabitants of Atlantis who survived the sinking of the city. The inhabitants are threatened by the semi-immortal evil ruler whose wickedness provoked the sinking. but he is ultimately defeated and the explorers return safely to the surface, teh young student with an Atlantean bride. Aspects of this story strongly remind me of Tolkien's Numenor, especially the character of the villainous ruler. ( )

One of Conan Doyle's much less well known works, this short novel was published in 1929, the year before his death. It tells of a mission by Professor Maracot (a Challenger-like figure) to explore the ocean depths where he and his companions come across the survivors of Atlantis. They also encounter various sea creatures and a mysterious sinister devil-like figure, the Lord of the Dark Face, which is apparently a Blavatsky creation, which demonstrates the spiritualism that formed a key part of the author's mental landscape in his final years. A reasonable read, feels very like Jules Verne. ( )

England, ca 1926
Dr. Maracot har en teori om at trykket ikke stiger med havdybden. Han udstyrer en ekspedition og lader sig og Scanlan og Cyrus J. Headley sænke i dybet fra skibet Stratford, dog kun 600 meter ned på en bjergryg, der omkranser et vældigt dyb, som han beskedent kalder Maracot dybet.
Et stort krebsdyr tiltrækkes af lyset fra dykkerklokken og klipper kablerne over, så de ryger ned på bunden. Det er held i uheld, for her genfinder de det sunkne Atlantis og opdager at trykket er til at holde ud og at Atlantis folket har etableret sig komfortabelt i dybet. Maracot bliver venligt modtaget, men får ikke vist alt frem, så de må snige sig lidt rundt for at finde en Molok eller Baal statue, der stadig ser ud til at være i brug. I nærheden møder de også Pallas Athene som er gudinde for de græske krigsfanger, Atlantis folket har taget med i dybet. Det er heldigt for Maracot kan snakke klassisk græsk med dem omend det er svært at gøre sig forståelig.
Der er forresten ikke mørkt, for havbunden er dækket af fosforiserende dynd. De får et chok da de opdager vraget af Stratford, som er forlist i en cyklon. Efter at have begravet kaptajn Howie og de to styrmænd i havbunden, bjerger de skibets logbog og funderer over det ironiske i at kaptajnen troede at de var omkommet i dybet.
Headley bliver kærester med lederen Manda's datter Mona og til slut stiger Maracot og de tre andre op vha en kugle af sejt glas og kommer tilbage til civilisationen.
Her beretter de om en kamp med Baal-Sela, som er en inkarnation af Djævelen. Da næsten alt håb er ude, beder Dr. Maracot til de højere magter og de hjælper ham.
Headley er også overbevist om reinkarnation og om at han og Mona har kendt hinanden tidligere.
De stiger op fra dybet og lever sikkert lykkeligt til deres dages ende.
Doyle er virkelig god til at dele historien op, så det virker naturligt at man stille og roligt får det hele at vide. ( )

The Maracot Deep and Other Stories was ACD's last collection of his fictional work. It was published in 1929, the year before he died.