The Thing on the Doorstep recap

Daniel Upton explains why he killed his friend Edward Derby at Arkham Sanitarium. Edward marries occult student Asenath Waite and begins suffering lapses in which another personality controls his body. He eventually claims that Asenath can exchange minds with him and that her body is actually inhabited by her dead father, the sorcerer Ephraim Waite. Edward says he kills Asenath, but his symptoms return and he is committed. After the apparent Edward is released as sane, a decaying figure arrives at Daniel's door with a written message: Edward's mind is trapped in Asenath's buried corpse, while Ephraim has taken Edward's body permanently. Edward asks Daniel to kill that body before Ephraim can continue. Daniel obeys, shooting his possessed friend and accepting the consequences.

Daniel Upton opens by acknowledging that he fired six bullets into the head of his friend Edward Derby at Arkham Sanitarium. He expects to be judged a murderer but believes the history of their friendship provides another explanation. Edward was a brilliant and unusually sheltered child, devoted to poetry and forbidden learning but poorly equipped for independent life. Daniel, several years older, becomes his closest companion and watches his interests deepen into serious occult study. Even as an adult, Edward remains dependent on his parents and emotionally vulnerable. Daniel presents this background as essential to understanding how someone else could gain such power over him.

Daniel has admitted killing Edward and described his friend's sheltered upbringing and occult interests. Edward meets Asenath Waite, an intense Miskatonic student from Innsmouth and the daughter of the late sorcerer Ephraim Waite. The pair marry and move into an old Arkham house with three servants from Innsmouth. Edward's friends become uncomfortable with the household, while his behavior grows erratic. He suffers periods of missing time, turns up far from home without knowing how he traveled, and sometimes displays a confidence and expression unlike his usual self. At other moments he appears terrified of Asenath and hints that she can push his consciousness out of his body. Daniel also sees Edward driving past with a look so alien that he doubts his friend is controlling himself.

Edward eventually arrives at Daniel's home in panic and gives a fuller account of the exchanges. He says Asenath can occupy his body while forcing his mind into hers. More disturbingly, he believes the mind using Asenath's body is actually Ephraim Waite, who escaped death by displacing his daughter and now wants Edward's body as a stronger permanent home. During the conversation Edward abruptly changes manner, retracts everything, and leaves when Asenath arrives. Later he returns in apparent freedom and says Asenath has gone away, then privately admits that he killed her and concealed her body in the cellar. His relief does not last: the seizures and changes of personality resume. Daniel has him committed to Arkham Sanitarium for protection, but the personality within Edward soon appears calm and competent to the doctors. Daniel recognizes Asenath's characteristic manner in his friend and realizes that the hospital may release the wrong mind in Edward's body.

Daniel receives a night visitor whose small, shrouded form is badly decayed and unable to speak. It delivers a letter written by Edward. The message confirms that Ephraim had long ago taken Asenath's body and that the mind now occupying Edward's living body is Ephraim. When Edward killed Asenath's body, the final exchange left Edward imprisoned in that corpse. He has forced the dead body out of its cellar grave and brought Daniel the warning before it collapses completely on the doorstep. The letter asks Daniel to destroy Edward's body so that Ephraim cannot continue using it. Daniel goes to Arkham Sanitarium and shoots the apparent Edward six times. He is left awaiting trial for the visible crime of murdering his friend, while the condition of the thing at his door and Edward's written account provide the only explanation for why he believed the killing necessary.

A misshapen, foul-smelling visitor arrives at Daniel Upton's door and gives him a letter. The visitor is the reanimated body of Asenath Waite, which Edward Derby had buried in the cellar. Edward's mind is now trapped inside that decaying body, while Ephraim Waite's mind has secured permanent possession of Edward's living body. The letter explains that Ephraim had taken Asenath's body years earlier and later used it to gain access to Edward. Unable to speak, Edward has forced Asenath's corpse out of the grave long enough to warn Daniel and ask him to destroy the usurper. The corpse collapses at the doorstep. Daniel goes to Arkham Sanitarium and fires six bullets into Edward's body, killing the being that occupies it. He tells the story while awaiting judgment, convinced that the shooting was necessary even though the law can see only the murder of his friend.