The story opens with John Bartine saying he's not sure what the time is, and angrily handing his watch to the narrator before stomping off to gaze at a bookshelf. The narrator sets his own watch by Bartine's heavy pocket watch, and he notices that Bartine seems extremely agitated. The two had shared a friendly evening and were now relaxing at home, so the narrator is not sure why Bartine has any reason to have such an emotional outburst.
The narrator finally asks Bartine why he reacted in such a way. John Bartine explains that the watch has been in his family for three generations, its original owner being his grandfather, Bramwell Olcott Bartine, a Tory who lived in Virginia. He provided an unspecified service for someone else who was loyal to the British, and a pack of rebels attacked him at his home. He was marched away from his family and swallowed up by the darkness; his body was never found. Though no sign as to the fate of Bramwell was ever found, his watch turned up at the doorstep of the family home a few weeks after his disappearance. It was wrapped in paper bearing the name of Bramwell's son, who was John Bartine's grandfather. Bartine also curses Washington and his damned rebels.
Bartine explains that he likes the watch and so he always keeps it with him, but every evening he feels a powerful compulsion to open it even if he does not wish to know the time, and when he does, experiences a terrible sense of dread. These emotions become more and more intense the closer time gets to 11 pm every night, but after this time passes, the desire to look at the watch vanishes. John has therefore trained himself not to look at the watch before 11. Therefore, he was quite upset when his friend asked him to check the time.
The narrator is intrigued by this odd case of apparent mental illness in his friend, who is otherwise intelligent and well balanced. He decides to conduct a little experiment, and asks to see the watch again. When he opens it, he notices a little portrait that looks exactly like his friend John Bartine. When the narrator mentions this to his friend, Bartine explains that this is a portrait of his great-grandfather, Bramwell. When Bartine looks away, the narrator carefully turns the hands on the watch back one hour, changing the time from nearly 12 to almost 11.
He then hands back the watch to Bartine, and casually says that, since it is nearly 12, he wouldn't mind looking at the watch now. John Bartine pulls out the watch and does so, but a terrifying look crosses his face and and curses his friend for turning the clock back - it is two minutes to 11. John Bartine starts to shake and then falls to his knees, dead. A post-mortem examination found a faint mark around his neck, as if he had been hanged, and the narrator speculates that Bramwell Olcott Bartine must have been hanged at 11 at night.
The narrator of the story is never named, but the subscript of the story is "A Story by a Physician." From this, together with the fact that he decides to undertake an "experiment" (62), the reader may infer that John Bartine's friend is a doctor or scientist of some kind. The peculiar choice to refrain from naming a character places greater focus on John Bartine, whose name appears in the title of the story.
The title of the story, "John Bartine's Watch," may have a double meaning, referring to both the physical object of the timekeeping device, but also to the vigil that John Bartine keeps every night in unknowing imitation of his ancestor's death, gazing at the pocket watch.
Bramwell Olcott Bartine is referred to as a Tory, an eighteenth-century term for someone who remained loyal to the British during the Revolutionary War. It is likely that he took action in an attempt to prevent the rebels from winning the Revolutionary War, and so was killed for it.
It is not entirely clear that John Bartine and Bramwell Olcott Bartine are two different people. Bramwell Olcott Bartine's body was never found after he was marched off into the night by rebel troops, and it is possible he may have escaped somehow. There are two additional clues as well. One is the description of the portrait of Bramwell Olcott Bartine in the watch as looking exactly like John Bartine, to the point that "This portrait is you in every feature, line, and expression" (62). Secondly, Bartine's peculiar outburst at the "traitorous" Washington and his "ragamuffin" rebels (60) seems peculiar for someone who is three generations removed from such events, and who lives in a country that hails Washington as a founder and central hero. A final clue is the last sentence of the story, "May God rest his soul in Paradise, and the soul of his Virginian ancestor, if, indeed, they are two souls" (64).
What does it mean if John Bartine and Bramwell Olcott Bartine are the same person? Could Bramwell Olcott Bartine have been transported through time to the present? Did he manage to dodge his death sentence through the powers of the watch? Was John Bartine in fact Bramwell Olcott Bartine's reincarnation of sorts, and did this mysterious timekeeping device somehow inflict the death of the one on the other? In true Bierce fashion, it is challenging to assign a clear explanation to the events of the story; instead, it is the myriad possibilities and interpretations that keep the reader's attention.