A wounded crewman, now healed, appears with his sword, crazed to kill Klingons and “even the score” (even though he is no longer hurt.) Kirk and Spock observe the alien hovering above---they note that it grew more vibrant when the crewman expressed a lust for vengeance and violence.

“It exists on the hate of others,” Kirk concludes.

“It has acted as a catalyst to that violence,” Spock adds, and suggests that to defeat it “all hostile emotions must cease.”

At this point the Enterprise has only a short time before its dilithium crystals fail and the ship will be helpless far from Federation space. With the help of Kang’s wife, Kirk meets with him, but Kang won’t buy it. “We are hunters,” he says. “We take what we want.”

“There’s another way to survive,” Kirk says. “Mutual trust and help.”

There’s some swordplay and a vintage Captain Kirk speech, aggressively delivered as counterpoint to its meaning. “The good old game of war—pawn against pawn---stopping the bad guys, where somewhere something sits back and laughs---and starts it all over again.”

“Those who hate and fight must stop themselves,” Spock says, “otherwise it is not stopped.”

“Be a pawn, be a toy, be a good soldier who never questions orders,” Kirk taunts Kang.

Kang sees the entity, finally believes it is manipulating them, and throws down his sword. “Klingons fight for their own purposes,” he says.

“Cessation of hostilities have weakened it,” Spock observes. He suggests good spirits might do it in.

Kirk tells the entity to go away. “We don’t want to play. We know about you. Maybe there are others like you around, maybe you’ve caused a lot of suffering, a lot of history, but that’s all over. We’ll be on our guard now. We’ll be ready for you.”

“Only a fool fights in a burning house,” Kang cries, and joins in the general laughter, and even slaps Kirk on the back. (If you take a look at this episode, don’t miss Spock’s expression in the background after Kang’s back-slap.)

Notably, the episode ends here---there is no coda or final scene of the Enterprise bridge crew discussing the mission and joking around.