This story begins with a passage written in archaic English, declaring that the serpent's eyes has a magical property that spells the death of any who gazes into them.
Harker Brayton smiles as he reads this peculiar sentence in a volume called Marvells of Science, amused by the antiquated nature of such a belief. He lowers the book as he ponders this idea, and sees two small specks of light at the corner of his room. He dismisses them as reflections of the gas jets above him.
Later, though, he again puts the book down and sees these little points of light. He notices that they have a greenish hue, and have moved slightly closer to him. He resumes reading until something in the text makes him drop his book again, and he gets a closer look at what exactly is staring at him - a giant serpent!
This seems like a horrifying supernatural occurrence, but actually there is a very rational explanation for the appearance of a great serpent in a San Francisco apartment. Brayton is staying at the home of his friend, Dr. Druring, who is a distinguished scientist with a special interest in snakes. He has actually created an entire wing of the house that he calls the Snakery in order to house the animals - though one or two of them do occasionally escape. Keeping this in mind, Brayton feels an instinctive shudder of loathing but is not greatly affected by the sight of the serpent.
He considers ringing the bell to summon a servant, but is concerned that this will seem to demonstrate a fear that he certainly does not feel. The snake looks quite large, but he reasons that if it's not poisonous, it's simply matter out of place, no threat at all.
Still, he rises and decides to back slowly away from the creature, knowing that there are numerous weapons on the wall that he can use to kill the snake should it decide to attack. However, he is horrified to discover that he is unable to move backward, and in fact starts walking forward toward the snake. He tries to stop his unwilling forward progress toward the snake by hanging on to a chair, but stumbles.
Staring into the eyes of the serpent, he experiences a profound vision of splendor, including rainbow cities and the splendor of ancient civilizations by the banks of the Nile. He is startled out of this vision by a sharp blow. He has fallen to the floor and broken his nose. Though he has broken the spell of the serpent's state, he feels the compulsion to look back into its eyes. His face is only a few feet away from the beast, and he begins to convulse. Each movement brings him closer to the snake.
In another part of the house, Dr. Druring is regaling his wife with a description of his new acquisition - a snake that eats other snakes. His wife suggests that the animal does this through the powers of hypnosis, but Dr. Druring dismisses this idea. Suddenly they hear a scream, and rush toward the sound. They find Brayton on the floor, covered in blood and dead. Dr. Druring comments that he must have died in a fit, and then sees something else in the shadows. It is a stuffed toy snake with two buttons for eyes.
Perhaps unusually for Bierce, the supernatural is entirely absent in this story, though it does not seem so at first. The story leads the reader through a series of switchbacks: at first, we share Brayton's incredulity at the legend of the power of the serpent's eyes, then we begin to wonder about the truth of this legend upon the appearance of the snake in his room, then we are treated to a rational explanation for the appearance of this beast in the home of an eccentric scientist, then the legend is affirmed by the hypnotic power of the snake upon Brayton, and lastly we discover that the legend could not possibly be true because the snake is in fact a stuffed animal. The reader is led on a conflicting maybe/maybe not in which it is finally revealed that the supernatural has no role in the story.
Brayton initially laughed at the passage in the book describing the hypnotic powers of the serpent's eyes, but in the end he ends up dead after being "hypnotized" by a toy snake. Though the snake was not even real and Brayton professed that he didn't believe the superstition about the serpent's gaze, he ends up going into a fit and dying. This indicates that Brayton's subconscious belief in the power of the snake was his own downfall; if he had admitted some of his fear at reading this passage and immediately called a servant or ran from the room when he noticed the snake, he might have saved his own life.
Bierce may actually be mocking the weight that some individuals place on the supernatural in this story, in which the human imagination creates its own demise by believing in supernatural occurrences. However, it is peculiar that the strong emotions that Brayton experiences should induce his death, and may indicate that the supernatural has a more subtle role in this story.
The story also contains an intriguing example of synecdoche, a figure of speech in which a part of something is used to stand in for the whole. In this case, as Brayton is backing away from the beast, he thinks "Should the monster follow, the taste which had plastered the walls with paintings had consistently supplied a rack of murderous Oriental weapons from which he could snatch one to suit the occasion" (25). In this case, the taste refers to the taste of Dr. Druring, an eccentric scientist who has decided to hang a number of swords from the walls. This sentence is also an excellent example of Bierce's writing style, which demands the reader's full engagement and frequently represents the whole by its parts.