The story concerns the violent death of a woodsman named Morgan. The sole witness, Morgan's friend Harker, claims Morgan was attacked by an invisible creature. The jury dismisses Harker's incredible story, but the coroner may know more than he is willing to admit.
"The Damned Thing" can be found in many horror and supernatural anthologies. The story also appears in some science fiction collections because of the pseudoscientific theory presented regarding the nature of the mysterious creature.
Eight men have gathered in a small room in a cabin for an inquest. The coroner sits reading a notebook belonging to Hugh Morgan, the deceased owner of the cabin. The jury, local farmers and woodsmen, sit along the wall. Morgan's corpse lies on the table in the middle of the room partially covered by a sheet.
A young man enters. He is sworn in by the coroner, and the inquest resumes. The witness is a city newspaper reporter named William Harker who was with Morgan at the time of his death. Harker produces a manuscript which describes the events surrounding Morgan's death. He tells the coroner that he has written it as fiction rather than news because it is so incredible. He then reads aloud a section from the manuscript with the coroner's permission.
Harker and Morgan are quail hunting when they hear some animal thrashing about in a field of tall wild oats. Morgan tenses up and aims his gun as if he is expecting to see a grizzly. Harker asks what it is, and Morgan answers "That Damned Thing!" Harker sees the wild oats bend as if they are being crushed down by something invisible moving slowly towards them. Morgan begins to shoot at the movement.
Harker hears a savage scream. As Morgan begins to run away in terror, Harker is knocked down by something soft but heavy bumping violently into him. Morgan cries out. Harker hears vicious sounds similar to dogs attacking. Harker gets up and sees Morgan less than thirty yards away wrestling with something heavy and strong yet invisible. Morgan's body is being pushed and twisted around violently. Before Harker can reach him, Morgan goes down. The invisible thing moves away from Morgan and goes through the wild oats into the wood. Harker finds Morgan dead.
Harker has finished reading his manuscript. The coroner removes the sheet to reveal the naked body on the table. It is badly bruised and lacerated. The coroner then displays the torn, blood-stained pieces of clothing for the jury before asking them to go outside to consider the verdict. Before stepping outside, the foreman asks from what asylum Harker escaped.
Harker, having recognized Morgan's diary which the coroner has been reading, asks to see it. The coroner tells him the diary has no bearing on the case then slips it into his pocket. The jury returns to deliver the verdict: they find Morgan was killed by a mountain lion.
Although Morgan's diary is not entered as evidence, it contains some entries of interest. It is Morgan's dog that first reacts to the Thing. Next Morgan observes the stars along a ridge disappear from left to right as if something is passing in front and obscuring the view. Morgan begins watching for the Thing at night. Although he never sees it, he finds fresh footprints in the morning. After a month of hunting the mysterious Thing, the sleep-deprived Morgan grows afraid that he is losing his mind. He invites his level-headed friend Harker to spend time with him. Soon, however, the answer comes to Morgan in a sudden inspiration. There are ranges of colors that the human eye cannot see – and the Damned Thing is of such a color!