Life's major commitment, whatever it may have been, can no longer be followed. The future looks bleak. The prisoner's world falls apart. A deadly illness limits another person's life span. Or a crippling disease or accident terminates his major commitment, and his relationships are ended or drastically changed.
Life suddenly seems to be full of new and horrible fears, limitations or permanent frustrations.
It is the unchangeable nature of catastrophe that makes it so frightening. One lovely woman of the writer's acquaintance suffered an auto accident in which her face was horribly disfigured. Her husband forsook her. She could not stand for her friends to see her. She so hated her face that she could not even bear to look in the mirror.