The Moonstone

The Moonstone by Wilkie Collins, which was first serialised in 1868, is generally regarded as the first English language detective story of any length. The plot of the book centres around a sizable, priceless diamond that Colonel Herncastle stole from India during the Siege of Seringapatam. Herncastle decides to leave the diamond to his niece Rachel Verinder on her eighteenth birthday despite being shunned by his own family. At her birthday celebration, Rachel displays the Moonstone for all to see. Later that evening, the diamond vanishes from her room, and an immediate investigation is launched to identify the burglar and retrieve the gem.