E-book exclusive extras:

1) Christie biographer Charles Osborne's essay on Sleeping Murder;

2) "The Marples": the complete guide to all the cases of crime literature's foremost female detective.

Soon after Gwenda Reed moves into her new home, odd things start to happen. Despite her best efforts to modernise the house, she only succeeds in dredging up its past. Worse, she feels an irrational sense of terror every time she climbs the stairs... In fear, Gwenda turns to Jane Marple to exorcise her ghosts. Between them, they are to solve a 'perfect' crime committed many years before...

Of note: Agatha Christie wrote Sleeping Murder during World War II and had it placed in a bank vault for over thirty years.