Spock, Sulu, and Uhura are aboard the shuttlecraft Copernicus
en route to Starbase 25. They are delivering a Slaver stasis box, discovered by archaeologists on the planet Kzin. The Slavers were an ancient race who ruled the galaxies a billion years ago. The only source of knowledge about them is their stasis boxes that they left behind. Their stasis box starts to glow and Spock explains that it indicates the presence of another Slaver stasis box. The glow indicates Beta Lyrae, a rare stellar formation. Spock is skeptical that no one else has ever found a stasis box given it's an oft-visited phenomenon. Nonetheless, Spock orders Sulu to set course for Beta Lyrae to investigate. As they proceed, Spock notes that some slaver boxes have contained advanced technology and others contain undetonated explosives...Read the full recap
Larry Niven adopted his own Known Worlds short story "Soft Weapon" for this episode, the only Trek episode to feature his own Kzinti.
This is the only episode to not feature Kirk in the entire run of the original and animated series.
Sulu: Mr. Spock, if it takes a stasis box to find another stasis box, how did anyone ever find the first one?
Spock: As with a number of discoveries, purely by accident, Lieutenant.
Chuft Captain: What of the picture?
Kzin Telepath: The human, Sulu, believes it to be Slaver.
Chuft Captain: So do I. It would have made a worthy enemy.
Kzin Telepath: Captain, he is too alien. He makes me taste yellow root munched between flat teeth!
Chuft Captain: Be glad if you need not read the Vulcan's mind.
Spock: Consider. Chuft Captain has been attacked by an herbivorous pacifist, an eater of leaves and roots, one who traditionally does not fight. And the ultimate insult, I left him alive. Chuft Captain's honor is at stake. He must seek personal revenge before he can call for help.
Sulu: That gives us some time. You did plan it that way?
Spock: Of course.
Chuft Captain: They think very little of you.
Uhura: Wrong. They don't think very much of you.
Uhura: Didn't you say the Kzinti have legends of weapons haunted by their dead owners?
Spock: Yes, an ancient superstition.
Uhura: At this rate, they'll never get over those old superstitions.