In class, Walter Jameson, Kittridge's colleague for twelve years and future son-in-law, reads from a Civil War journal of Major Hugh Skelton. Kittridge is riveted by Jameson's reading - an account of the burning of Atlanta. He discusses the diary after class with Jameson and invites him to dinner that night.
That evening, as Jameson crosses the lawn to his home across the street from Kittridge's, he is observed by an old woman.
Kittridge is very proud of his daughter, Susanna, who is immersed in her studies and cautions Jameson that he is giving her hand to him, not her mind. Nevertheless, he will not allow much socializing. After supper, he sends her up to her room and her books.
As they resume a game of chess, Kittridge examines his colleague's hands and how different they look compared to his own. He asks Jameson how old he is. Jameson tells him he's 41, but Kittridge confronts him with the fact that he had given his age as 39 when he joined the university staff in 1947. He wonders why his friend does not seem to have aged at all. He pulls out a book of Matthew Brady photographs and shows Jameson a picture of General Sherman's staff, including Major Hugh Skelton. Down to the ring on his finger and a mole on his face, he is Jameson's perfect double. Jameson is forced to admit he is the same man.
Jameson explains that two thousand years ago, he was obsessed with living longer. He searched out the experts, but no one could help him until an alchemist took a great deal of his money and subjected Jameson to his experiments. Jameson isn't certain exactly how it happened but that he nearly died of the experiments. Believing they had failed, he went on living his life only to watch his friends and relatives age and die while he remained the same.
Kittridge, an old man afraid of dying, doesn't understand Jameson's weariness about this remarkable feat. His friend explains that death is what makes life worth living. He hasn't gotten any wiser. He has been forced to outlive his loved ones for centuries and he's tired of living. He keeps a gun in his desk at home that he pulls out regularly but is too cowardly to use it.
Kittridge realizes that Jameson will only have a few years to spend with Susanna before he will have to leave her. Jameson explains that he tried to resign a few months ago when he realized Susanna was falling in love with him and he with her. Now it's too late. When Kittridge forbids him to marry her, she overhears and Jameson convinces her to run away with him.
In his home, however, Jameson is confronted by the old woman who turns out to be one of his former wives who saw his picture in the newspaper announcing his wedding. She doesn't understand why she has aged and he hasn't, but she will not allow him to leave another wife. Using the gun from his desk, she shoots him. The noise brings Kittridge who watches him age quickly and dissolve into dust.
Susanna arrives and sees Jameson's clothes in the dust on the floor.