They glow, against the skin

1879: Captain Henry Marshal, of the East Surrey Regiment, discovers the treasures of Durr-i-Durran during Khost Valley expedition of the second Anglo-Afghan war. Writing to his betrothed, Agatha Best, Marshal mentions a network of caves under Khost containing a great store of treasure, and implies that he has appropriated some items from the Durranis: "Would that you had been there, my dearest Agatha, when I rounded a particularly tight corner in that squalid little rabbit-warren to discover such beauty. Not since last leaving your presence.... Perhaps your father will now look more kindly on my decision to join the Young Buffs...."

Five days later, in the mountainous territories east of Khost, Marshal is caught in a rockfall. His right arm is entirely smashed to pieces, necessitating amputation at the scene by Surgeon-Major Preston. Marshal arrives at the camp at Peshawar delirious, and dies shortly thereafter. Marshal's batman, George Eccles, arranges the safe passage of Marshal's personal effects—including some two dozen loose pearls, tightly wrapped in undergarments—out of the country.

1880: Eccles falls at the battle of Maiwand; Preston is wounded and returns home. The precise location of the riches of the Durrani passes once again into obscurity.

1883: Agatha Best, now Lady Agatha Hailsham, commissions a necklace to be made from the pearls. The task falls to the world-famous Houndsworth's, a specialist jeweller near Regent Street. Houndsworth's the company has a proud history, stretching back to Queen Elizabeth I's reign, and the grandfather of the company's founder helped work on Anne Boleyn's famous "B" necklace.

By the 1880s the company is in some difficulty. Nathaniel Houndsworth is in ailing health, but unwilling to hand the reins to his son Martin. The historian Andrew Gillman discusses Nathaniel Houndsworth's condition in some detail: "racked with pain from arthritis, symptoms of which were especially prominent in the swollen joints of his dominant right hand, Houndsworth could barely handle the jewels, let alone set them with any delicacy of touch." Michael Denning, an apprentice during the end of Houndsworth's running of the company, remembers the older man "bent over his desk like a question mark." He was clearly in terrible pain.

1884: The Khost Necklace is finished. The next day Houndsworth finds his hands utterly unusable: it is believed that his arthritis had been exacerbated by the stress of the company's last commission, and retires. Two months later, following a series of hysterical fits, he is confined in St Anthony's Hospice, Ramsgate. Lady Agatha wears the Khost Necklace to a number of prominent occasions that season.

1887: At the age of twenty-six, Lady Agatha has an accident while riding on the South Downs. She falls from the horse and lands on rocks, fracturing her skull and causing a blood clot in the brain. Although she survives with her wits intact, much of her right-hand side—arm and leg, and her facial muscles—are weakened by the accident. She is left unable to speak.

1902: Martin Houndsworth, son of the late Nathaniel, is convicted of fraud. The remaining assets of Houndsworth's are liquidated.

1922: The eldest daughter of Lord and Lady Hailsham dies of pneumonia, aged thirty-six. She leaves two sons, Andrew and Caspar, and a daughter, Emily.

1928: Emily Hailsham marries author and essayist Robert Cookson. Robert is a favourite of the Bloomsbury set, and is rumoured to be having an affair with both Virginia Woolf and at least one of the Mitford sisters.

Emily lives the life of a Bohemian authoress and bon vivant in London; her novels Out of the Water and A Troubled Paradise are released to widespread acclaim in 1929 and 1932. Later works, including Don't Worry About Her (1934), Never Again (1935) and A Lock of His Hair (1939), are received much less favourably and critical opinion gradually turns against her, prolonging her work on the ultimately unfinished The Burford Pariah.

1934: Lady Agatha dies, leaving Emily to inherit the Khost Necklace.

1944: During the British invasion of Nazi-occupied France, the now Sergeant Robert Cookson is killed on Omaha Beach. Eye witnesses later confirm his heroism: he attempts to return a live grenade to the enemy, but the ordnance explodes as it leaves his grasp.

1947: Leaving a society ball, Emily Cookson is involved in a minor accident: her writing hand is slammed in a car door, breaking several small bones. She hires a typist to continue work on The Burford Pariah, but her habit of heavy drinking gradually turns into alcoholism.

1948: With mounting financial problems Emily Cookson is forced to sell the Khost Necklace. No records exist of the sale, but it is believed to be at an unfavourable price to her major creditor, convicted thief and "spiv" Terry White: certainly Emily receives little actual money in return for the necklace.

1955: Emily Cookson dies of complications arising from delirium tremens.

1962: Terry White is found murdered; according to autopsy his body contained over two hundred bullets, and his "shooting hand" is itself shot entirely to pieces.

1969: The Khost Necklace resurfaces at auction. Little can be reconstructed about the intervening years, but three jewellers including Michael Denning himself (now aged 97) testify to the likelihood of its veracity. During surface transport to auction, the crate carrying the necklace falls fifty feet from a hoist, and another crate lands on top of it; the necklace is broken and some pearls are lost. The Khost pearls are eventually sold singly to a number of private investors.

1973: Bryan Stanley Johnson, avant-garde author, commits suicide; a pearl, believed to be from the Khost Necklace, sits beside the bath in which he is found. Friend and agent Michael Bakewell later admits to receipt of the manuscript inspired by Johnson's acquisition, Pearls Before Swiving, or The Nature of the Beast, but it is destroyed during a failed burglary.

1977: Musician Marc Bolan dies in a car accident. On his right finger is a gold ring with a Khost pearl inset, believed to be a gift from David Bowie. This pearl, like Johnson's, is bought by a private foreign investor.

2002: Yvonne Chevalier, "holistic healer to the stars", buys the five pearls previously unaccounted for. Four of these are ground down to form part of an expensive treatment against skin ageing, and Chevalier is feted by the rich and famous. Soon afterwards, however, her soldier son Hal disappears during the battle of Shahi-Kot in Paktia Province. Chevalier becomes a vocal anti-war campaigner, while Hal, with the keepsake given to him by his mother, is declared missing in action.