- Old Dr. Heidegger, a peculiar individual, invites four of his elderly friends over to his study one night. His guests are: Mr. Medbourne, who was once a rich merchant but lost all his money on speculation; Colonel Killigrew, who is suffering in old age from the wild lifestyle he lived when he was young; Mr. Gascoigne, a ruined politician who is now all but obscure; and the Widow Wycherly, who was once beautiful but whose reputation had long ago been ruined.
- The first-person narrator informs us that, at one point, all three men had been the Widow's suitors, back when they were all young and foolish. They nearly killed each other competing for her.
- Now we get a good look at Dr. Heidegger's study, which is a very odd place indeed. It is dusty and old-fashioned. There are several bookshelves stuffed with papers and quartos. One features a bust of Hippocrates which, supposedly, Dr. Heidegger consults with from time to time. In one corner is a closet with a skeleton inside. There is also a large mirror; rumor has it that all Dr. Heidegger's dead patients live in there and will look at you if you peer into it.
- There is also the large portrait of a woman, once the Dr.'s fiancée, who very unfortunately took one of his prescriptions the night before their wedding and died.
- Most interestingly, says the narrator, is a large black folio with silver clasps that is supposed to be magic. Once, when the cleaning lady tried to pick it up, the skeleton rattled in its closet, the young lady stepped out of the portrait, and the bust of Hippocrates said, "Forbear!" (A fancy word for "Cut that out!")
- Anyway, back to the summer afternoon of our story. Dr. Heidegger has set out four champagne glasses and a large, beautiful vase on the table in his study. As his guests take their seats, Dr. Heidegger asks for their help in an experiment.
- The narrator notes that Dr. Heidegger is a strange man, and that the narrator himself is the source of many of the stories that circulate about him. If you don't believe him as you read, he'll just have to accept that.
- Back to the story. Dr. Heidegger opens his mysterious, magic black folio with the silver clasps and removes an old, withered rose. This rose was given to him fifty-five years ago, he explains, by his now-dead bride-to-be. He then drops the old, withered rose into the vase on the table.
- The guests peer at the rose on the surface of the water. It quickly regains its color and youth and soon appears as though it has just bloomed. Dr. Heidegger's guests think it is a nice parlor trick.
- But Dr. Heidegger explains that this was no magic trick. He asks if his guests have ever heard of the Fountain of Youth. As the story goes, Spanish conquistador Ponce de León went looking for the mythological fountain in Florida and never found it.
- Recently, explains Heidegger, his buddy in Florida found the fountain and sent some of the water to Heidegger.
- Colonel Killigrew is skeptical. He asks what the water is supposed to do for a person.
- Dr. Heidegger promises that it will make them young again. He himself has no desire to return to youth – he's had enough trouble the first time around – but his guests are welcome to try it. He fills the four champagne glasses with water from the vase.
- Before the four guests drink, Dr. Heidegger offers them a warning. They ought to remember what they learned from their first youth. They shouldn't make the same sort of mistakes again.
- Of course, reply the guests, and they drink. Sure enough, they sense themselves beginning to grow younger. They clamor for more water, but Heidegger tells them "with philosophic coolness" to chill out and be patient (25). Still, he pours them another round, which they drink.
- The men start acting a little weird; either the water is making them drunk, or "the sudden removal of the weight of years" is making them dizzy (28). Mr. Gascoigne is occupied thinking about politics, though it's unclear whether he's dealing with politics of the present or the past. Colonel Killigrew is belting out drinking songs, and Mr. Medbourne is preoccupied with money matters.
- The Widow, who we remember used to be beautiful, runs to the large mirror to check out her new, young self. She's ecstatic with her looks. The four of them dance around and mock the old-people clothes that they're wearing.
- Meanwhile Heidegger is just sitting back like "Father Time" and watching this scene play out (32). The Widow asks him to dance with her, but he says he's too old and recommends one of the other men instead. This sets the three men at each other's throats over who gets to dance with the Widow.
- Oddly enough, the mirror in the corner of the room shows a strange reflection; in it, the four guests still appear to be elderly. No one notices this, however.
- As the three men fight over the Widow, they tussle and wrestle and knock over the vase full of water from the fountain of youth, which hits the ground, shatters into a thousand pieces, and spills the water across the floor.
- A butterfly, old and near death, catches its wings in the water and is immediately made young and lively again. It flies over to Dr. Heidegger and settles on his snowy head.
- Dr. Heidegger asks that his guests please calm down and he picks up his rose from the shattered fragments on the floor.
- The three men stop their fighting and look over at Dr. Heidegger. The rose is his hand begins to shrivel up again. "I love it as well thus as in its dewy freshness," says the Doctor (47). The butterfly, at that point, falls dead to the floor.
- The four guests begin to feel that they, too, are growing old again. They cry out.
- Dr. Heidegger affirms that this is the case, and points out that the water from the fountain of youth has all been spilled on the floor. He does not regret this, however; watching the four of them has taught him a lesson, and he wouldn't drink from the fountain for anything.
- The four guests, however, do not share the Doctor's point of view. They vow to travel to Florida, find the fountain, and drink from it morning, noon, and night.