The story begins with a newspaper article about the murder of Hildred Falrath, a retired psychology professor, at the hands of his former student, Clement Van Dorn. Van Dorn, who had been receiving private instructions from Falrath, claims self-defense, noting that Falrath, despite being wheelchair-bound for years, attacked him first.

The narrator, an unnamed character, is visited by Michael Costigan, a massive, almost primitive man who brings up ghosts and his own haunting past, including a fatal boxing match where he inadvertently killed his opponent, Battling Rourke. Costigan expresses a fear of the supernatural, claiming he senses a presence and sees shadows in his room, hinting at a psychological struggle or possible haunting.

Costigan's narrative of eerie experiences in his apartment parallels another account by Professor Falrath, found in an unfinished letter, suggesting a similar supernatural or psychological phenomenon involving sensing and partially seeing spectral figures in the darkness. The story hints at a deeper, possibly occult influence affecting individuals linked by past violence or trauma.

The story then shifts to another scene where the narrator discusses the murder case with friends, expressing skepticism about Van Dorn's violent capabilities given his intellectual and passive nature. They visit Van Dorn in prison, where he recounts the horrifying transformation of Falrath into a monstrous entity before attacking him, a claim that suggests either a supernatural occurrence or a psychotic break.

The narrative includes another subplot involving Michael Costigan's eventual suicide after experiencing severe hallucinations or ghostly visitations, further complicating the theme of specters both as literal ghosts and as metaphors for haunting memories or guilt.

In a twist, the narrator's sister, Joan, appears suddenly, claiming her idealistic and non-violent husband Malcolm has brutally beaten her, introducing a shocking contradiction to Malcolm's established character and beliefs, and adding another layer of mystery and darkness to the story.