Uncle Silas is a Victorian Gothic mystery-thriller novel by the Irish writer J. Sheridan Le Fanu. It is notable as an early example of thelocked room mystery subgenre. Like many of Le Fanu's novels, it grew out of an earlier short story, "A Passage in the Secret History of an Irish Countess" (1839), which he also published as "The Murdered Cousin" in the 1851 collection Ghost Stories and Tales of Mystery. The novel is a first person narrative told from the point of view of the teenaged Maud Ruthyn, an heiress living with her sombre, reclusive father Austyn Ruthyn in their mansion at Knowl. She gradually becomes aware of the existence of Silas Ruthyn, a black sheep uncle whom she has never met, who was once an infamous rake and gambler but is now apparently a fervently reformed Christian. Silas's past holds a dark mystery, which she gradually learns from her father and from her worldly, cheerful cousin Lady Monica: the suspicious suicide of a man to whom Silas owed an enormous gambling debt, which took place within a locked, apparently impenetrable room in Silas's mansion at Bartram-Haugh.