The story opens with a grim murder in a southern lumber camp. A violent black worker, Joe Cagle, shoots a white overseer named Harry, brother of Joan, the story’s heroine. Before fleeing into the surrounding pine woods, Cagle threatens to return for Joan — a promise that fills her with dread.

The unnamed narrator, Steve, a Texan rancher who loves Joan, vows to join the posse hunting Cagle. The searchers scour the forest and swamps but find nothing. Steve learns of a nearby “Deserted House,” a decayed mansion avoided by all the locals because of its sinister history — strange deaths and supposed hauntings. Believing Cagle might take refuge there, Steve rides into the black heart of the woods alone.

At midnight, the moon rises as gunshots echo ahead. Steve finds the house and enters cautiously, his horse fleeing in terror. Inside the dusty ruin, he discovers Cagle’s corpse — unmarked by wounds but twisted in an expression of utter horror. The revolver by his hand shows every chamber fired.

Moments later, Steve sees a monstrous shadow move across the wall — a huge, apelike silhouette with no visible source. It stalks him through the moonlit rooms, its unseen body casting only its shadow. In panic, Steve fires wildly until his gun is empty and finally crashes through a locked door and leaps from a window to escape. He falls unconscious outside.

When he awakens, Joan is there — she had followed his trail, fearing for him. Steve tells her Cagle is dead and hints at a horror beyond words. She recalls a forgotten local story: decades earlier, a circus gorilla escaped into the house and had to be killed there. Soon after, the house’s owner fell to his death from an upstairs window, and later a traveler who spent the night also died the same way.

Steve realizes that the haunting “shadow of the beast” is the lingering spectral presence of that gorilla — a savage, bestial spirit haunting the place. To end its reign of terror, he burns the house to the ground as dawn breaks, believing the fire will finally destroy the monstrous ghost and lift the curse from the pine lands forever.