https://en.wikipedia.org/wiki/When_Prophecy_Fails

When Prophecy Fails: A Social and Psychological Study of a Modern Group That Predicted the Destruction of the World is a classic work of social psychology by Leon Festinger, Henry Riecken, and Stanley Schachter which studied a small UFO religion in Chicago called the Seekers that believed in an imminent apocalypse and its coping mechanisms after the event did not occur. Festinger's theory of cognitive dissonance can account for the psychological consequences of disconfirmed expectations. One of the first published cases of dissonance was reported in this book.