"The Promise" starts a few months after "The Chosen" left off, with Danny having just started his graduate program in psychology and Reuven having started rabbinical school. The novel begins in the summer of 1950 when Reuven is dating a college student named Rachel Gordon. Rachel and Reuven take Rachel's cousin, Michael Gordon, to a carnival, where Michael has a mental breakdown over a carnival game. In the coming days, Michael's father Abraham Gordon, a secular rabbi and teacher, informs Reuven that Michael has a history of mental illness and that he will probably need to live in a treatment home with psychological oversight. Abraham Gordon, a friend of Reuven's father, is a controversial figure; Gordon's books, which question the existence of God but seek to reconcile these questions with Jewish tradition, have caused him to be placed in cherem; Gordon keeps a scrapbook of the many times he has been attacked in the press.