E-book exclusive extras:1) Christie biographer Charles Osborne's essay on They Do It with Mirrors;2) "The Marples": the complete guide to all the cases of crime literature's foremost female detective.A sense of danger pervades the rambling Victorian mansion in which Jane Marple’s friend Carrie Louise lives—and not only because the building doubles as a rehabilitation centre for criminal youths. One inmate attempts, and fails, to shoot dead the administrator. But simultaneously, in another part of the building, a mysterious visitor is less lucky. Miss Marple must employ all her cunning to solve the riddle of the stranger’s visit, and his murder—while protecting her friend from a similarly dreadful fate.The New York Times: ‘No one on either side of the Atlantic does it better.’