'Does anyone believe what happened at the Reichenbach Falls?' reads the opening of novel sanctioned by Conan Doyle estate

Anthony Horowitz, who was first sanctioned by the Conan Doyle estate to tell a new Sherlock Holmes story three years ago, is plotting a return to the world of the super sleuth in a novel set days after Holmes and his nemesis Moriarty apparently plunged to their deaths over the Reichenbach Falls.

Horowitz found a good reception for The House of Silk, in which an elderly Watson recounted the tale of one of Holmes's early adventures. "Can [Horowitz] astonish us? Can he thrill us? Are there 'the rapid deductions, as swift as intuitions, and yet always founded on a logical basis' that we yearn for?" asked Ian Sansom in a Guardian review at the time. "Emphatically, yes. The characters are, as Conan Doyle himself would have them, as close to cliche as good writing allows."

Now the author, best known for his Alex Rider series of young adult novels about a teenage spy, has announced that Moriarty, a new novel set in the world of Holmes, will be published on 23 October.

"Does anyone believe what happened at the Reichenbach Falls?" it will open, referring to Holmes and Moriarty's infamous plunge over the Swiss waterfall. Conan Doyle wrote of the battle in 1893 that "any attempt at recovering the bodies was absolutely hopeless, and there, deep down in that dreadful cauldron of swirling water and seething foam, will lie for all time the most dangerous criminal and the foremost champion of the law of their generation".

Conan Doyle had hoped to kill off Holmes, tired of the character who had made him famous and keen to focus on more serious writing, but the public outcry at the much-loved detective's death meant he was forced to resurrect the famous inhabitant of 221b Baker Street. "I've written a good deal more about him than I ever intended to do," he said in 1927, 40 years after the first Holmes story was published, "but my hand has been rather forced by kind friends who continually wanted to know more."

Horowitz's tale will take place shortly after the events in Switzerland described by Conan Doyle, as Pinkerton agent Frederick Chase arrives in Europe from New York. "The death of Moriarty has created a poisonous vacuum, which has been swiftly filled by a fiendish new criminal mastermind who has risen to take his place," revealed publisher Orion. "Ably assisted by inspector Athelney Jones of Scotland Yard, a devoted student of Holmes' methods of investigation and deduction, Frederick Chase must forge a path through the darkest corners of the capital to shine light on this shadowy figure, a man much feared but seldom seen, a man determined to engulf London in a tide of murder and menace."

The publisher said that Moriarty would be "very different in nature to Horowitz's previous bestseller; but fans will be delighted to see a few surprise guests from the Conan Doyle's canon making appearances in the new book".

Horowitz himself revealed on Twitter that "Sherlock Holmes does not appear (until the very end)", that "a vicious murder is investigated by Inspector Athelney Jones (from The Sign of Four)" and that "nearly all the policemen Holmes ever worked with, including Lestrade, appear in my new book".

"Look out for the appearance of the 'dreadful' Abernetties. One of the most famous untold Holmes stories," he said, adding that the book would take place in Camberwell, Mayfair, the London Docks, Highgate and Smithfield.

Horowitz is also a screenwriter, creating television series such as Midsomer Murders and Foyle's War. Orion made the disputable claim in its announcement about the forthcoming Moriarty that he "may have committed more (fictional) murders than any other living author".