A famous actor is sent to his death from a high window; eye witnesses say he was pushed by an invisible hand, thus echoing another murder committed in the same house more than fifty years earlier. Three local girls have also died in similar inexplicable fashion, propelled from the top of Wish Tor, a rocky outcrop in the wilds of Dartmoor. Is there an invisible creature roaming the sinister and forbidding landscape? Or is there a human agency behind the murders and, if so, how is it done? The renowned criminologist Dr. Alan Twist and the irascible Inspector Archibald Hurst of Scotland Yard are sent to investigate…