A coded warning of imminent danger sends Sherlock Holmes and Dr Watson to the fortress-like country house of the reclusive Jack Douglas. When they arrive too late to prevent a tragic death, the great detective and his chronicler must follow a series of bewildering clues to find a murderer who has vanished into thin air. Only then will they solve the mystery of the dead man's desperate plea: 'Am I never going to get out of the valley of fear?'