At the climax of the story, what does Sanger Rainsford have an epiphany about?
Rainsford realizes that the general is toying with him when he turns back, and he decides he will need to up his game and not lose his nerve.
When Rainsford is first told by General Zaroff that he is hunting human beings, he is shocked. He accuses the general of murder, and tells him that he is not a murderer and will not participate. Unfortunately, what he does not realize at the time is that he is about to become the prey and not the hunter. Zaroff tells him that he is bored, and the implication is that Rainsford will make an interesting game! Even hunting people has become tiresome.
The hunt is very lopsided. Rainsford is given only “khaki hunting clothes, a haversack of food, [and] a leather sheath containing a long-bladed hunting knife” to fight against Zaroff’s guns, dogs, and assistant Ivan.
On his side, is extensive hunting experience. While he may never have been the prey, he has often been the hunter. Rainsford decides to give Zaroff a trail to follow. He is reasonably confident at first, as he has small successes in evading his pursuer.
However, when Rainsford sees Zaroff turn back and hears him compliment him, he realizes something. This really is a game to Zaroff, even if it is deadly.
Rainsford did not want to believe what his reason told him was true, but the truth was as evident as the sun that had by now pushed through the morning mists. The general was playing with him! The general was saving him for another day's sport! The Cossack was the cat; he was the mouse. Then it was that Rainsford knew the full meaning of terror.
Rainsford is focused on not losing his nerve, but it is difficult for him to realize how good Zaroff really is. Until this point, he thought he was doing well, and had some advantages in being the prey and being able to evade instead of pursue. At this point, he realizes that he is in deep trouble.
From here on, Rainsford turns deadly serious too. He sets a trap that kills Ivan (even though it was meant for Zaroff), and another that kills one of Zaroff’s best dogs. Zaroff does not seem to be getting angry. He still seems to enjoy the hunt.
"You've done well, Rainsford," the voice of the general called. "Your Burmese tiger pit has claimed one of my best dogs. Again you score. I think, Mr. Rainsford, I’ll see what you can do against my whole pack. I'm going home for a rest now. Thank you for a most amusing evening."
Rainsford realizes that he has to turn the game to his advantage. He gets the idea of taking the “wild chance” of swimming to the chateau to confront Zaroff. There, he kills Zaroff, telling him he is still a “beast at bay” when Zaroff tells him he was won the game and it is all over with. Although killing Zaroff was not part of the game, Rainsford is changing the rules. The man who wanted not to be a murderer no longer has confidence that Zaroff will ever let him go if he does not kill him first.
Rainsford has to acknowledge that he is not going to get out of this situation alive by just evading Zaroff. The hunter is too good, knows the island too well, and has too many advantages. Rainsford has to turn the tables by doing something Zaroff does not expect. Since Zaroff is enjoying himself and does not feel threatened, Rainsford decides that he is going to win and is just prolonging things. In order to get out alive, Rainsford's only way out must be to kill Zaroff, and turn his back on his principles.