Quick Guide: Slaughterhouse-Five
Slaughterhouse-Five explores fate, free will, and the illogical nature of human beings. Protagonist Billy Pilgrim is unstuck in time, randomly experiencing the events of his life, with no idea of what part he will next visit (re-live) — so, his life does not end with death; he re-lives his death, before its time, an experience often mingled with his other experiences.
Billy Pilgrim says there is no free will, an assertion confirmed by a Tralfamadorian, who says, "I've visited thirty-one inhabited planets in the universe . . . Only on Earth is there any talk of free will." The story's central concept: most of humanity is insignificant; they do what they do, because they must.