The Golden Age of Murder. Martin Edwards

established a reputation as a detective novelist, and the couple had named their house Styles, after the scene of the crime in her debut novel, The Mysterious Affair at Styles.

      When the police called at Styles, they spoke to Charlotte (‘Carlo’) Fisher, who acted as Christie’s secretary and helped to look after her daughter Rosalind. Carlo said the author had left home, driving off without telling anyone where she was going. According to Carlo, Christie had been unwell recently, and her family were worried about her. Christie’s husband Archie was staying with friends, along with his secretary Nancy Neele. He’d recently confessed to Agatha that he’d fallen in love with Nancy.

      The police took Archie and Carlo to the spot where the car had been found. The news had already leaked out, and the car was surrounded by a crowd. The area rapidly became a magnet for sensation-seekers, and the Press salivated over the puzzle, indulging in feverish guesswork about the mysterious affair of the beautiful young writer, and her dashing war hero husband. Words of wisdom from Superintendent Kenward, the Deputy Chief Constable of Surrey Police, featured prominently in their reports.

      ‘The most baffling mystery ever set me for solution’ was Kenward’s quotable description of the case. An early theory was that Agatha had crashed her car and wandered into nearby woodland in a disorientated state and become lost. The area was searched, with help from members of the public, but there was no sign of Agatha. When questioned by the police and newspapers, Archie was defensive. He dreaded the truth about his relationship with Nancy coming to light. The police guarded his house, and monitored his phone calls.

      ‘They suspect me of doing away with Agatha,’ he told a business colleague. To deflect suspicion, he revealed to the Daily News that his wife had been thinking of ‘engineering her disappearance’. The newspaper offered a £100 reward for information leading to her discovery, helpfully printing a set of photographs showing how she might have altered her appearance with a disguise.

      Close to Newlands Corner, in a hollow shaded by box trees, lay the Silent Pool. Fed by underground springs, the water was clear and still. A woodcutter’s daughter had been surprised there by wicked King John, so legend said, while she was bathing naked. She drowned while trying to flee from him. Her ghost was seen by local people from time to time, floating on the surface of the pool.

      Had Christie chosen this serene yet spooky place to end her life? There was only one way to find out. The Silent Pool was dredged with the aid of a pump and large grappling irons to slash the weeds. Tractors and a light aircraft scoured the countryside, and dogs searched the land. They found no sign of a corpse.

      With each passing day, the theories became wilder. A clairvoyant called in by the Daily Sketch suggested that Agatha’s body might be found in a log-house. Cynics suggested that the ‘disappearance’ was a stunt to publicize her latest novel, The Murder of Roger Ackroyd. Or had she disguised herself in male clothing and gone into hiding, like Dr Crippen’s mistress Ethel Le Neve sixteen years earlier? The Daily Express consulted a former Chief Inspector of the CID, Walter Dew, renowned as ‘the man who caught Crippen’, who reinvented himself as an occasional media pundit on matters criminal and mysterious after retiring from Scotland Yard. Dew doubted whether Christie was the victim of foul play, or had vanished for publicity or financial reasons. ‘All women are subject to hysteria at times,’ he pronounced, opining that perhaps the fact that she ‘thought about crooks and murder all day’ had affected her. Reporters thirsting for sensation found leading crime writers equally keen to share their wisdom.

      On Friday 10 December, Dorothy L. Sayers (whose father had jumped to ‘a scandalous explanation’ of the puzzle) wrote about the case for the Daily News. She assessed the possible scenarios: loss of memory, foul play, suicide, and voluntary disappearance, but her article was apparently written without personal knowledge of Christie’s character. Her speculations highlighted the questions about the case, but yielded no answers.

      Was Agatha conducting a form of ‘mental reprisal’ against someone who had hurt her? Edgar Wallace advanced this theory in the Daily Mail, guessing that she was taking revenge on Archie for his adultery. A year or so later, Wallace wrote a story inspired by the case, ‘The Sunningdale Murder’. The Daily Mail also featured Max Pemberton, author of several bestselling Victorian thrillers, fearing the worst. He thought Agatha was dead.

      Sherlock Holmes’ creator, Sir Arthur Conan Doyle, was a former Deputy Lieutenant of Surrey, although he had resigned after developing a passionate belief in spiritualism. He had investigated real-life crimes, such as the Edalji and Oscar Slater cases, with much success. The Surrey police supplied him with one of Agatha’s gloves, which he took to a medium and psychometrist named Horace Leaf. Leaf’s considered opinion was that ‘trouble’ was connected to the glove. If this insight was of limited value, Leaf did say that Agatha was still alive. Conan Doyle informed Archie of this breakthrough, and announced that the case was ‘an excellent example of the uses of psychometry as an aid to the detective’.

      The police appealed for public help in searching the Surrey Downs, and ‘the Great Sunday Hunt’ took place on 12 December. About two thousand civilians took part, wrapped up warm against the cold. It was like a massive outdoor pre-Christmas party. Ice creams and hot drinks were sold from vans to refresh the spectators. Sayers could not resist joining in the excitement, and persuaded John Gilroy, her artist friend from Benson’s, to drive her to the Silent Pool. The outcome for her was even more of an anticlimax than her foray to France to investigate the Nurse Daniels mystery. During a brief look around, Sayers failed to spot any tell-tale clues that the police had missed, and was left to pronounce, with all the authority she could muster, ‘No, she isn’t here.’ Yet if she failed to contribute to the detective effort, at least her day out amounted to useful research. Aspects of her visit featured in Unnatural Death, in which two women go missing from a car left abandoned on the south coast.

      As darkness fell, the hunt was called off. A flare was lit to help searchers who had lost their bearings find their way home. Weary and deflated, Kenward told journalists that he did not believe Agatha Christie’s disappearance was a gimmick designed to sell her books.

      What he did not know was that the answer lay more than two hundred miles north. A banjo player and a fellow bandsman performing at the Hydropathic Hotel in Harrogate, the North Yorkshire spa town, were keeping a close eye on a woman guest. They concluded she was the missing novelist, and their detective work proved superior to anyone else’s. Within forty-eight hours, the whole world learned that Agatha Christie had been discovered, safe and well.

      After travelling by train to Harrogate, Christie had taken a first-floor room at five guineas a week and bought herself some new clothes, including a glamorous pink georgette evening dress. She followed the reports about her disappearance in the Press, and played bridge – and billiards – in the public rooms. At night she danced in the Winter Garden Ballroom to the music of the Happy Hydro Boys. Otherwise she relaxed by having massages, solving crossword puzzles and borrowing books from the W.H. Smith’s lending library. Her favourite reading comprised thrillers rejoicing in titles such as The Double Thumb and The Phantom Train. She had assumed the identity of a Mrs Teresa Neele, recently returned to Britain from Cape Town. Her chosen surname was that of her husband’s mistress.

      Today Agatha Christie remains, almost half a century after her death, a household name. More than that, she has become a global brand. Big business. Two billion (or is it four billion? – estimates vary, and at such a stratospheric level, it scarcely seems to matter) copies of her books have been sold, and she has been translated more often than any other author. About two hundred film and television versions of her work have been screened, and the stories have been adapted into video games, graphic novels and Japanese anime. She was the most performed female British playwright of the twentieth century, and The Mousetrap is the longest-running stage play of all time, with more than 25,000 performances in London alone. The sixtieth anniversary of its first performance was celebrated by sixty specially licensed performances worldwide. Her home overlooking the River Dart is in the care of the National Trust and a popular tourist destination, while her native Torquay boasts an Agatha Christie Mile, along which visitors can retrace her steps.

      A statue featuring