E-book exclusive extras: Christie biographer Charles Osborne's essay on The Murder at the Vicarage; "The Marples": the complete guide to all the cases of crime literature's foremost female detective.

The murder of Colonel Protheroe — shot through the head — is a shock to everyone in St Mary Mead, though hardly an unpleasant one. Now even the vicar, who had declared that killing the detested Protheroe would be 'doing the world at large a favour,' is a suspect — the Colonel has been dispatched in the clergyman's study, no less. But the picturesque English village of St Mary Mead is overpopulated with suspects. There is of course the faithless Mrs Protheroe; and there is of course her young lover — an artist, to boot.