The story takes place at the University of Maine in 1966. Peter Riley, a Freshman at the University of Maine, gets addicted to playing Hearts in the all-male dormitorywhere he lives. The games are lead by Ronnie Malenfant. Although their student draft deferments have shielded them from serving in the Vietnam War (the reason why Peter compares the university to the mythical Atlantis, hench the title of the story), Peter and the growing number of students addicted to the game put themselves at risk as their studies suffer.
Peter eventually meets Carol, Bobby Garfield's childhood friend. Carol herself uses student activism as an escapist addiction of her own. Although they fall in love, Carol comes to announce that she will be leaving school. She explains that her decisions are forever influenced by the help that Bobby had given for her. She and Riley make love for the first time in his car. The next morning, she leaves a note warning him to stop playing Hearts.
When Stokely Jones, another student activist, slips and falls in a rainstorm and nearly drowns, Peter is disturbed by the strange way he and the other boys first laughed at Jones's misfortune before helping him. He finds he is shaken from his Hearts addiction and resolves to turn his grades around. Shortly afterward, Jones is accused of having sprayed "FUCK JOHNSON" on a campus wall, with the dormitory floor proctor reasoning that the peace signs accompanying the message lead to Jones. However, Peter and the others point out that they, too, have been toting peace signs, undermining the accusation and saving Jones from punishment.
Peter barely passes his classes and is saved from being drafted. He receives a package from Carol containing a newspaper article of a protest she participated in. Malenfant is expelled from campus due to his bad grades, and send to Vietnam.