Toby Jugg, a fighter pilot shot down in combat, is now confined to his bed with little hope of walking again. He is also the heir to a considerable fortune - a fortune that is being administered by a board of trustees until he comes of age.
At night, he is becoming increasingly disturbed by a strange presence - a mysterious shadow thrown by the moonlight through a gap in the blackout curtains. He is convinced the shadow is cast by a malevolent and unnatural entity trying to get into his room. Toby is unable to convince anyone of the reality of this entity, and slowly comes to believe that there is a ploy against him, a plot to send him mad, or to make it appear that he is already mad in order to usurp his fortune. Is this some form of hallucination? Is this unearthly creature real or a product of his imagination? Are the people caring for him actually plotting his destruction, or are they sincerely concerned for a young man whose grip on sanity is steadily weakening?
With themes of love, madness, Communism, Satanism and Freemasonry, Wheatley builds his trademark atmosphere of menace, suspicion and supernatural dread.