Fans of Sherlock, the BBC detective drama based on the novels of Sir Arthur Conan Doyle and which ended its second series on Sunday night, have pooled their wits in a bid to crack the mystery.
In the climax to the three-part series, Sherlock Holmes, played by Tinker Tailor Soldier Spy star Benedict Cumberbatch, stood on the roof of St Bartholomew’s hospital in central London and telephoned his best friend and side-kick Dr Watson, played by The Office’s Martin Freeman, to bid him farewell.
He is then seen leaping from the parapet and striking the pavement, before being carried away without a pulse and bleeding from the head by paramedics.
His apparent motive: to deter a team of assassins working for Moriarty, his nemesis, from murdering his friends as they hunted a computer code only Holmes could reveal.
But as Watson visits his friend’s grave months later, the detective is revealed to be alive and well and watching from afar.
Internet message boards were abuzz with theories yesterday as a legion of armchair sleuths pondered how Holmes, the detective known in literature for cracking difficult cases in the time it takes to smoke three pipes, faked his own death.
Eagle-eyed viewed noted that there was no crash mat or conveniently-placed skip of rubbish to provide a soft landing for the detective, who plummeted face-first over six storeys.
Some fans suggested that the body was a dummy.
Others claimed the falling man was really Moriarty, who moments earlier had himself committed suicide on the rooftop by putting a gun in his mouth. It is suggested Holmes had wrapped his nemesis in his overcoat and tipped his body over the ledge.
Significantly, as he runs to reach his apparently dying friend, Dr Watson is hit by a cyclist and tumbles, dazed, to the pavement.
Some fans suggested the crash was arranged by Holmes to buy him enough time to run from the rooftop to the street and pretend to be fatally injured before being whisked away.
Moments after the body strikes the pavement, one careful viewer noted, a refuse lorry can be seen pulling alongside – allowing the detective to swap places with a body.
Another viewer suggested the suicide act Dr Watson had witnessed never took place.
In last week’s episode, The Hounds of Baskerville, a hallucinogenic drug was used to trick the pair into seeing a terrifying wild dog. Could Sherlock have used a similar chemical agent to trick his friend?
At the heart of the riddle, viewers agreed, lies Molly Hooper, Holmes’ pathologist friend who works at St Bartholomew’s. She could have helped cover-up the fake suicide by taking charge of his post mortem examination, providing a false death certificate and even supplying cadavers.
The mystery is thickened by the fact that in The Final Problem, the short story on which the episode was based, Holmes really does die.
Sir Arthur was convinced the detective stories were distracting him from more serious literary pursuits and his hero had to be killed off. “I must save my mind for better things,” he wrote to his mother.
In the 1893 work, Dr Watson concludes Holmes and Moriarty die in a scuffle at the top of Reichenbach Falls, the Swiss waterfall, after finding footprints which show the pair toppled over the edge to their deaths.
But the ambiguity of the ending, and the lack of witnesses to Holmes’ demise, allowed Conan Doyle to delight his fans by resurrecting the detective years later.
The solution to Sunday’s enigma will be revealed in time. The show’s creators, Mark Gatiss and Steven Moffatt, confirmed on Twitter on Sunday that a third series had been commissioned.