The Slaver Weapon

Spock, Sulu and Uhura are taking a Slaver stasis box, a relic of an ancient empire, to Starbase 25 in the shuttlecraft Copernicus when it signals that another box lies nearby. Landing on an icy planet to investigate, they are captured by the Kzinti, warlike felines posing as privateers, who have used their own empty box as bait. The Federation box is opened. Inside are some meat, a picture of a Slaver and a strange device that proves to be a weapon with many settings. Control of it changes hands more than once, and Sulu discovers it can fire a total conversion beam. When the Kzinti seize it again, they find it contains its own war computer. Unable to give the right code words, they ask for the most powerful setting, and the computer directs them to a self-destruct. The weapon explodes, killing the Kzinti, while the three officers survive.