It's difficult to find a traditional notion of "climax" in Wiesel's work. It makes sense to a great extent because so much of what Wiesel has presented is so beyond traditional configurations. I would say that a particular apex of action is reached when Eliezer's father dies. There is so much in this moment that is haunting and reflective of Eliezer's own sense of change and development that the father dying is one of the last connections to his own past. The father begging his son for water, asking why his son is being ignored, and Eliezer simply ignoring such cries only to wake the next morning to the bed of his father being empty is a climactic moment because it represents how different Eliezer's experience had made him. From the boy who listened to Moshe's experience about wishing to ask God "the right questions" to a being where survival is all that matters and to one where the traditionalist notions of right/ wrong have been inverted to a level where all reality had lost the moral compass of ethical direction, the death of Eliezer's father is one of those moments where so much had transpired. It also helps to bring out the full meaning of the ending whereby Eliezer does not fully understand the reflection that stares back at him.