The Slaver Weapon
In the shuttlecraft Copernicus, Spock, Uhura, and Sulu are en-route to Starbase 25 to deliver a stasis box -- a rare artifact of the Slaver culture. The now-extinct Slavers used these objects to carry weapons, valuables, and other scientific instruments and data. The boxes can detect each other and evidence shows that another device is located nearby. The shuttle lands on an ice planet where hostile Kzinti lie in ambush.