Inspired by the Ripper murders of 25 yrs before, Belloc Lowndes wrote this story in 1913, a gripping claustrophobic tale describing the impact on an impecunious ageing couple, the Buntings, when an eccentric stranger comes to stay as lodger.Mr Sleuth is a good guest, pays handsomely and in advance, needs very little looking after and seems to be a harmless gentleman.But when the murderous exploits of a serial killer known only as 'The Avenger' start occurring closer to home, Mrs Bunting begins to worry about her guest, his curious experiments and nocturnal habits.The tension is held throughout and the real identity of the culprit is not fully exposed until the close of an excellent psychological thriller packed with horror and suspense.