Narbondo

Deep beneath the quicksands of Morecambe Bay lies a shifting graveyard of lost things, long sunk to the sea bottom. Pursued by the nefarious Dr. Narbondo, Langdon St. Ives and his stalwart companions descend beneath the sands in a diving chamber, and amid the debris of human bones and the wreckage of human lives, they search for an alien device, which, in the wrong hands, could change the course of human history and provide Narbondo with the means to enslave mankind....

Deep within the cavern-riddled chalk cliffs above the English Channel there brews a threat to the very sanity of the people of Britain. A startling madness infects the members of the Explorer's Club in London, the debacle coinciding with the disappearance of Alice St. Ives and the murder of the lighthouse keeper at Beachy Head. Langdon St. Ives sets out to rescue his wife and to stop the accelerating train of events hurtling he and his friends into a dark tunnel of madness and death.

A strange message summons Langdon St. Ives and his companions to the Half Toad Inn in Smithfield, London, and along with the eccentric but fabulously wealthy Gilbert Frobisher, they set out for an uncharted island in the Caribbean, carrying a map that promises a treasure that beggars description. What they find — a terrible, pagan god from the depths of the ocean — leads them back to London, carrying within the hold of Frobisher's steam yacht a fearsome, tentacled menace that threatens to devastate London.