Whodunnit? Was it the fog, the opium, the quicklime, the Ceylonese twin or his villainous uncle Jasper that did for Edwin Drood?
The BBC is about to finally provide an answer and expose the murderer, in a new adaptation of Charles Dickens' unfinished novel, The Mystery of Edwin Drood, to be screened this summer.
Dickens died in 1870, exhausted by overwork and his gruelling public performances, before he could reveal all.
He had finished two-thirds of the book, and caused Drood to vanish in mysterious circumstances, when the author had a stroke on 8 June and died the following day without regaining consciousness, leaving only a sketchy outline for the remainder of the novel.
The story will be completed this time by the film and television script writer Gwyneth Hughes, responsible for last year's acclaimed BBC serial Five Days.
The BBC is not revealing Hughes' final twist of the plot, but the hot money must be on John Jasper, the opium-addled uncle and choirmaster at Cloisterham cathedral – a scantily disguised Rochester in Kent, near Dickens' last home at Gad's Hill, whose cathedral, castle and narrow streets appear in many of his books.
In Dickens' version Jasper is a rival of both his nephew Edwin, and the smitten Ceylonese twin Neville, for the affections of the heiress Rosa.
In most film and television adaptations since the first silent movie versions in 1909 and 1914, it turns out that Jasper strangled his nephew, burying the body in a pit of quicklime which somebody has helpfully pointed out as they walk to the cathedral.
This was apparently Dickens' original idea, but he also wrote teasingly to his biographer John Forster: "I laid aside the fancy I told you of, and have a very curious and new idea for my new story. Not a communicable idea (or the interest of the book would be gone), but a very strong one, though difficult to work."
In the 1935 version, matinee idol Claude Rains as Jasper, his crimes revealed, eventually leaps to his death from the top of the bell tower. In the most famous recent version, made in 1993, Robert Powell's Jasper is last seen smiling evilly to himself in a condemned cell.
Edwin Drood is one of a string of Dickens adaptations the BBC is launching as part of its Year of Books season, in advance of next year's bicentenary of the author's birth. The season will include a BBC1 dramatisation of Great Expectations, and Radio 4 versions of A Tale of Two Cities and Martin Chuzzlewit.