The Sign of the Four

London, 1888. Mary Morstan asks Holmes to discover why her father disappeared after returning from the Andaman Islands and why an unknown benefactor has sent her a valuable pearl each year. A summons from Thaddeus Sholto leads Holmes, Watson and Mary to Pondicherry Lodge, where Bartholomew Sholto has been murdered inside a locked room and the treasure expected by his family has vanished. Chemical traces, footprints and the tracking dog Toby direct the investigation towards Jonathan Small and his companion Tonga, ending in a pursuit along the Thames.

Small’s confession carries the case back to Agra during the Indian Rebellion of 1857. He and three Sikh soldiers murdered a merchant carrying a deposed ruler’s jewels, concealed the Agra treasure and were later transported to the penal settlement in the Andaman Islands. Major Sholto’s betrayal brought the secret to England and created the chain of concealment, greed and revenge that Holmes must unravel. Watson’s growing attachment to Mary gives the novel a personal conclusion alongside Holmes’s demonstration of scientific detection.