Dr Jekyll and Mr Hyde by Robert Louis Stevenson

Published as a 'shilling shocker', Robert Louis Stevenson's dark psychological fantasy gave birth to the idea of the split personality. The story of respectable Dr Jekyll's strange association with 'damnable young man' Edward Hyde; the hunt through fog-bound London for a killer; and the final revelation of Hyde's true identity is a chilling exploration of humanity's basest capacity for evil.

(Penguin Book)