An army lieutenant named Klimov is returning home to his sister and aunt in Moscow and falls ill while on the train. His mouth is dry, his brain turns to mush, and he keeps hearing a strange voice cry, "Is the mail ready?" When he finally arrives at the station, he collapses. During the next days or weeks, he thrashes around his bed in delirium, latching onto disconnected images of a cheerful doctor, a grave priest, and various acquaintances and events.

One morning Klimov awakens feeling well. His whole being is filled with a sensation of happiness. He learns from the doctor that he has survived a case of spotted typhus. But where is his sister Katya? His aunt groans, "Ah, Katya, Katya! Our angel is gone! Is gone!" Indeed, Katya had caught typhus from her brother and died. Her funeral had taken place the day before. Pavel's "heart ached, he burst into tears, and leaned his forehead against the window frame."